Insulin and Regulating Diabetes


Insulin injection problems - What if it goes IM and not SQ

Question: Hi Drs, hope you're getting a break from all the weather in florida. Now, dont ya'all just sit out on your porch and watch it like you did last time, OK?? You gotta lotta clients depending on you!! I have a cat who can be very fractious when he gets his insulin. Once in a while instead of it going in SubQ, i think it went in intramuscularly. I try not to let that happen but sometimes he just jerks sideways just as I'm depressing the plunger on the syringe. He's on 6.0 units bid. Does it hurt more that way but more importantly, does the insulin still do its job regardless of the mode of administration?? He's been on 6 units for a couple of years and I cannot seem to get his glucose below 200-225 mg/dl. I tried chromium and vanadium with him but it didn't seem to make any difference in the blood sugar measurements. Thanks, catwoman.

Answer: C-

There is some difference in the rate of insulin absorption if it is given IM or SQ but usually not enough to cause any noticeable problems. I know of at least one vet who advocates using IM insulin injections because the rate of absorption and duration of effect are supposed to be more consistent. However, using standard insulin syringes I think that it would be hard to actually make intramuscular injections consistently since the needle length is pretty short. Switching to needles of an appropriate length and size for IM injection would make the injection less comfortable for the cat, probably (it is always hard to be certain of this sort of thing without someone actually trying it). From a practical standpoint if you occasionally make in IM injection I don't think it would cause enough problems for you to be able to see a difference. If you accidentally make an intradermal injection, which would be painful, the insulin probably doesn't work well because it takes some time for it to be absorbed from the skin. This is possible with the short and narrow gauge needles that are commonly used for insulin administration. If this happens too often try not to make the injection at a very shallow angle into the skin. It is hard to make an intradermal injection if you make the injection at right angles to the skin surface or at some angle close to 90 degrees.

You might consider trying the new glargine insulin (it is a human insulin that is new) to see if it works better. I have no idea what its cost is in comparison to other insulins but in a study done in Australia (or maybe New Zealand) of glargine insulin combined with a high protein/low carbohydrate diet (like Purina's DM (tm) diet) all 6 cats in the study were well controlled and eventually could be maintained with the diet alone --- these were newly diagnosed cases, not a chronic case, so the results probably won't be that good for cats whose insulin is switched. Glargine does give another option in the effort to get diabetes under control, in any case.

If you haven't tried using a high protein / low carbohydrate diet you might consider doing that. It really does seem to help with control of diabetes in cats (based on our clinical experience --- not necessarily a scientific assessment).

Mike Richards, DVM


Insulin glargine (Lantus Rx) and Purina's GLUCOTEST litter

Question: Dr. Richards,

Are you familiar with the insulin LANTUS?? Being a owner of a cat with diabetes (4 months), I am trying to obtain as much information as I can to be better educated. While researching types of insulin, I found this one. It appears to have great features, no peaking, constant concentration, and only given once a day at bedtime. Of course this information was on a site talking about human diabetes. So I did not know if it has been used on cats, and your opinion.

Currently my 13 year old is on NOVOLIN N (NPH) 2 units in am and 1 unit pm. If the Lantus is "cat friendly", how bad would it be to switch?

Also what is your opinion of Purina's GLUCOTEST granulas in the litter instead of the strips?

Thanks ahead of time!


Answer: Suzy-

Insulin glargine (Lantus Rx) was approved in the year 2000 for use in humans. I can not find any information relating to dogs and cats and this insulin the veterinary literature. I suspect that someone is probably studying its use since it does sound like it has some very good properties for use in people. I will try to keep an eye out for more information on this.

If you are doing well with the NPH insulin it is probably best to stick with it until more information is available. In general, though, switching insulin products works a little better than the initial regulation of pets with diabetes but generally involves a week or two of more intense monitoring to get things regulated again.

I really prefer to use blood testing for blood glucose levels over urine testing and so I haven't really tried Purina's litter that is supposed to be helpful in monitoring glucose. I suspect that it would work as well as glucose test strips, though. I do have some clients who have difficulty with blood testing and use urine test strips so I suspect we will give the litter a try at some point.

Mike Richards, DVM 11/11/2001

Insulin administration and renal failure

Question: I am a subscriber and appreciate any advice you could offer. We have four cats. Three are 13 and one is 11. Our 13 year old female kitty, Sasha has always been healthy and very petite at 8 lbs. She has had allergies (mostly sneezing) for the past 3 years for which she received Depo injections every 4-7 months. One sinus infection one year ago. Aug 31, 2000 we noticed excessive drinking and frequent urination. To vet next day for blood test. Results: glucose 439 (dx of diabetes). Other levels: Uvea nitrogen 46, creatinine 1.7, total protein 8.9, ALT (SGPT) 160, globulin 5.5, triglycerides 381, phosphorous 5.6, BUN creatinine 27, absolute lymphs 534. Starting 9/5 Sasha stayed at vet's office for 4 days for glucose monitoring and regulation of insulin. Brought her home on 9/8 using 2 units of Humulin L every morning with food. She seemed fine. 9/10 Frequent visits to litter but no urination. Drinking water. Urinalysis revealed cystitis. Injection of antibiotic. 9/15 Back to vet for glucose check. Reduced insulin to 1 unit per day. 9/22 Glucose normal 9/27 Lethargic, not eating, frequent urination, generally looked like she felt terrible & also had a green discharge from her nose. 9/28 Blood test: glucose 23, urea nitrogen 109, creatinine 5.2, total protein 9.3, phosphorous 16.4, globulin 5.9, amylase 1855, CPK 604, GGTP 45, magnesium 2.7. We discontinued insulin and had subq fluids. She was eating and feeling fair for a day but gradually became lethargic with no appetitie. For the next 4 days, Sasha went to the vet at 8am for IV fluids until 5:30pm so she could come home to sleep with us. She likes to be next to us ALL THE TIME. She also had antibiotic injection every day for the sinus infection. The next few days, she was given subq fluids and has had it every other day since then. 10/4 blood test: glucose 225, urea nitrogen 76, creatinine 3.3, phosphorous 10.5, CPK 664, Osmolality calculated 339, triglycerides 75. Tomorrow I am taking her back in for subq fluids and our vet will show me how to administer fluids at home. I think it will be less stressful for her that way. I wonder if the insulin brought on the kidney failure. We have always watched our cats carefully and noticed nothing until this incident. She has been eating w/d for the past 5 years. We are now giving her c/d dry and a/d canned to help her gain some weight. We like our vet and he has a good reputation. Please help us help our little girl. We can't imagine ever being without her.

Thank you. ileana

Answer: Ileana-

I am not aware of a link between insulin administration and renal failure in cats or dogs. It is not unusual for older cats to have some loss of kidney function, though. It is also not unusual for diabetic animals to become dehydrated due to the effects of the diabetes. Even mild dehydration can be very hard for compromised kidneys to compensate for and the result can be a sudden worsening of the kidney failure. It would not be unusual for cats to have both kidney failure and diabetes, since both occur in the same age range. I can't say for certain that there was not a reaction to insulin leading to the problem with the kidneys but I do think it would be very unusual.

Diabetic pets frequently have bladder infections as a complication of the disease. The sugar in the urine compromises the immune system and may also provide a better environment for bacteria to grow in. So this was not an unexpected complication with the original blood sugar values and it is one that you will have to continue to keep an eye out for if the sugar levels rise again.

Based on the labwork, I think that you are eventually going to have to treat for both diabetes and kidney failure. It is hard to be certain in a cat that diabetes is present with a blood sugar level in the low 200 range since cats can elevate their blood sugar when stressed, but this value, combined with the previous value of 400+ makes it highly likely that the diabetes will not be transient for long.

We have had a couple of cat patients who needed 1/2 unit of Humalin-N twice a day. They did find with this dose but had problems with no insulin at all. I use Humalin-N but there is no reason not to use Humalin-L. It might be worthwhile to consider trying glipizide (Glucotrol Rx) to see if an oral hypoglycemic agent might control the diabetes without the use of insulin. This only works about 30% of the time but it is an option for some cats.

It isn't a good idea to feed a cat with kidney failure c/d diet. It acidifies the urine and the kidneys do better with basic urine. This isn't a major problem but even with cystitis present it is still better to feed a low phosphorous, low to moderate protein diet that slightly increases urine pH. Hill's k/d, Purina's NF and several other diets are available for this purpose.

It is good that you are learning to give fluids and plan to keep it up. That helps a lot in keeping cats comfortable and will be especially important if the diabetes does continue to be a problem.

Good luck with all of this. Mike Richards, DVM


Insulin reactions and regulation

Question: Dear Dr. Richards,

Thanks for the reply to my original questions regarding my cat's (Lucia) diabetes/asthma conditions. We've done a great deal of reading on the subject (mostly on your website) and have tried some of the things that you have suggested to try to get her more closely regulated. Unfortunately, I am one of the people who couldn't draw blood from her ear (not for a lack of trying), so we've been doing a more clinical approach to regulating her, as suggested by our Vet. Her eating habits have been fairly typical of a diabetic; she eats and drinks a great deal and her weight has stabilized at about 7 pounds (4 1/2 pounds lighter than before the diabetes). Her asthma hasn't been a problem of late, so she hasn't had any Cypro or any other asthma treatment lately. There are several things that still concern me, though.

(1) She still likes to lay on cooler surfaces, such as hard wood or tiled floors, which to me indicates a possible elevated body temperature (although our Vet said it was normal the day he checked). Her ears are still very warm when the insulin has been administered fairly recently, but cool when it is time for an injection. (we're doing 7 units of Humulin N twice a day). Is this normal ?

(2) Although she lays down a great deal, we never really see her sleep. Do elevated glucose levels cause sleeplessness ?

(3) Our Vet says that the highest dose of insulin is equal to her weight in pounds, which means we are at the limit, although I feel she's not getting enough, given her continuing diabetic tendencies. Is my Vet correct that 7 units is the limit for a 7 pound cat ? If so, how can she ever be regulated if she doesn't gain any more weight ?

Thanks for your advice, I think she's come a long way, but still has a way to go.


Answer: John-

I think that some pets do have reactions to insulin injections and that sometimes itchiness, wheals or flushing of the skin can occur. These types or reactions are not supposed to be very common but we have had at least one or two clients report noticing similar reactions to insulin in their cats. If this causes more severe problems, such as itching or wheals, it might be a good idea to consider changing insulin types to see if that helps, but I wouldn't be in a hurry to do this unless it really seems necessary.

I am not sure why Lucia would now prefer to be on the cool areas of the floor rather than warmer spots.

I can not find any references to sleeplessness in cats who are diabetic. Cats nap frequently and often do not sleep for long periods at any one time, but if this is a new sleep pattern I do not know if it could be related to the diabetes, or not.

Your vet is incorrect that there is an upper dose limit for insulin use. There are only two reasons to limit the insulin dosage --- if the current dosage is working properly and if the amount of insulin necessary to control diabetes becomes completely impractical to administer. I understand what your vet is worried about, though. It is really hard to find information on maximum dosages of insulin in the standard veterinary textbooks. Dogs and cats who require insulin dosages above 1 unit per pound of body weight are considered to be suspect for insulin resistance. This is a reason to look for a cause of insulin resistance, such as concurrent hyperadrenocorticism, acromegaly, antibody production against the insulin, or other problems --- but it is not a reason to stop raising the insulin dosage to provide adequate control of blood glucose levels. It is pretty scary to give 20 units of insulin to a 7 pound cat, but this sort of dosing is sometimes necessary. If your vet is uncomfortable using higher dosages of insulin and there is not adequate control of the diabetes, it would be best to ask for a referral to an internal medicine specialist.

Mike Richards, DVM


Getting regulated - diabetes in cat

Question: Dear Dr. Richards: Thanks for some great information online. I look forward to lots of up to date information. I have a quick question that I did not find an answer to in any previous letters. I have an 11 year old male cat, previously in great health, who was recently diagnosed with diabetes. To start off treatment, my vet put him on 1 cc of Humulin R twice a day. Three days into the treatment, he had a serious episode of vomiting food and water, not eating, cloudy eyes, and very reclusive. I gave him a few days to get back on his feet as the vet said that whatever you do, don't give him insulin if he's not eating. Anyway, we have had two additional episodes such as this. The insulin has not been increased yet as we have been waiting for the episodes of vomiting to subside. He goes for about 5-6 days and you can see he is getting a little better, trying to groom himself etc. Then he gets the upset tummy and we're back to square one. He still drinks large quantities of water and pees a lot. My questions are two: Is it possible that he is becoming dehydrated and the vomiting is a result of this? Need IV fluids? Ketone sticks show he is not in ketosis. Is it possible that this is simply a result of the diabetes and if we increase the insulin, he will simply feel a whole lot better and we can finally get him stabilized? Thanks for any advice you might have. My vet is starting to shake his head----not a good sign!!!!!


Answer: Carol-

Humalin R is regular (crystalline zinc) insulin. The duration of action of regular insulin is short, usually less than 8 hours. It is usually used to start insulin in patients with ketoacidotic diabetes who need rapid control of the diabetes and who are going to be monitored closely in a clinical setting to insure that the blood sugar is controlled. Typically, in patients who are doing well and are not exhibiting signs of ketoacidosis using Humalin N (NPH insulin), Humalin L (lente insulin) or possibly PZI insulin (Blue Ridge Pharmaceuticals, a division of Idexx), is recommended as the starting insulin, due to a longer duration of action and more even control of blood glucose levels over the course of the day. Your vet may have had a specific reason for starting with Humalin R, or may have had success with this approach, despite it being a little unconventional.

It is definitely possible that the vomiting could be caused by complications of diabetes, including dehydration and ketoacidosis, even though you are not seeing signs of ketones in the urine. Gaining good control of the blood glucose levels should help. Using subcutaneous or intravenous fluids can help patients feel much better in some cases and should be used if dehydration is a problem.

I disagree with the advice about not giving insulin if the patient doesn't eat. The need for insulin does not go away because a cat doesn't eat. The need for insulin will be less if food is not taken in, but it won't go away. Unfortunately, it is hard to predict how much. Some veterinarians recommend decreasing the insulin dosage by half when a diabetic pet refuses to eat prior to the injection and some by lesser amounts. If the client is going to inject the pet with insulin and then go to work, we often recommend giving about 2/3rd of the dosage of insulin in this circumstance. If the client will be home with the pet all day, I'd prefer they stick to the dosage of insulin that seems to be working well and just observe the pet all day. Most of the time, after the insulin starts to exert an effect the pet will eat. There is a small risk of inducing hypoglycemia by following this course, but it is really hard to regulate insulin effectively if there are major ups and downs in the dosage administered on a daily basis. You do have to work this out with your vet, though ---- close communication is important and your vet's experiences and success with a particular technique have to be considered, even if they vary some from ones that work for another vet. If your vet is not having success in regulating the insulin dosage within a month, it may be best to ask for referral to an internal medicine specialist or to seek a second opinion on the treatment from another local vet. It often takes a month, and sometimes more, to really get good control of insulin dosage.

Good luck with this. If this has generated some additional questions feel free to ask them.

Mike Richards, DVM


New Diabetes diagnosis - getting regulated

Question: Dear Dr. Richards,

I am a new subscriber to vetinfo. We have an 18 year old male neutered cat, Suki.

On Monday 8/7, the veterinarian diagnosed him with diabetes. We got the prescriptions on Tuesday from him for Humulin N NPH 100, syringes, and ketodiastix. He received his first shot of 1 unit in the a.m. on 8/9. Ketones are negative on the stix, but glucose was 2000+. The vet then increased it to 1 unit a.m. and p.m. on Wed. evening. On Friday, the levels were the same. Ketones negative, but glucose 2000 +. He was increased to 2 units a.m. and 2 units p.m. Still no change. On Monday, he was increased to 3 units a.m. and 2 units p.m. At 4 p.m., (I came home early from work) his ketodiastix readings were negative for ketones and 250-500 on the glucose. I called my vet before giving him any more insulin and he told me to give him only 1 unit for his p.m. dose. He told me to expect the glucose to rise again when tested in the a.m. and sure enough it was 2000+ this morning. We gave him 2 units today. He is also on an antibiotic for 10 days as the vet said there was a little bit of blood in the urine and more for prevention than illness. The antibiotic is (I am not sure as I am at work) Betryl or something like that and I believe it is 22 mg. He has 4 more days to go.

Also, all other bloodwork that was taken came back negative and he is in otherwise good health. He has always been a hale and hearty cat and has never been sick a day in his life. He had lost some weight during his pre diagnosed diabetic days, but appears to be gaining again.

My question (s): Does this regimen sound correct to you? After researching the web and getting feedback, I am told that diastix are not reliable, insulin should be given for 4-5 days before changing dose, my vet is not experienced with diabetes, change vets, monitor blood at home for best testing. I am very new at this, as I have never had any experience with diabetes (family, friends or otherwise) and have been researching it for days and days. A lot of information and I tend to get confused with conflicting advice from well meaning people. Help! I am confused and need some verification that I am doing all the right things for my little boy.

You should also know that because we both work, he is fed at 5 a.m. and gets his shot about 6a.m. He is then fed again at 5p.m. and gets his shot about 6 p.m.

He always has access to food during the day. My vet said that while he wasn't happy with that, he did not want to stress him after this 18 year routine so leave it be.


Answer: I think that your vet is taking a reasonable approach to the induction with insulin. There is some reason to worry early in treatment of diabetes that even one unit of insulin will be too much. So starting with one unit and seeing what happens is reasonable, especially in a cat that is otherwise healthy. Then moving upwards for a couple of days fairly quickly when one unit doesn't cause problems and doesn't control the diabetes is very reasonable.

I do think that monitoring blood glucose with a glucometer at home is much better than using urine sugar measurements. It is possible to match the insulin dosage to the cat's needs much more accurately if this can be done. About 50% of the owners of diabetic cats in our practice can use a glucometer at home successfully. I feel bad when I recommend buying a glucometer and the clients can't use it routinely but lots of retailers will take them back for some time period, such as 30 days.

After you get close to the dosage that is going to be necessary to control the diabetes then it is a good idea not to adjust the dosage too frequently. We usually try to wait about three days between insulin dosage adjustments but this isn't always possible.

I think it is better for the cats to eat small amounts all day then to have two feedings a day, but I like the compromise of two controlled feedings a day with dry food free choice in between, too.

It doesn't really matter if your vet is highly experienced at treating diabetes. What matters is that he or she be really interested in treating diabetes and in particular treating it in your cat. This might sound odd, but getting control of diabetes is a matter of teamwork between the vet and the client and establishing a good working relationship is the single most important thing. If your vet wants this to work and is willing to listen to your questions and to address your concerns you will figure out the best way to manage the diabetes for you and for Suki.

If you aren't comfortable talking with your vet, you probably do need a new vet. If you know that you can go in with all the information you collect and talk it all over with your vet and that your questions will be answered thoughtfully, even if you don't totally agree with the answers, then you probably should stick with the vet you have. I think that it is fair for your vet to charge you for consultation and even research, in this circumstance, as long as it is really time spent for your benefit or your cat's benefit.

Hope this helps some. There is information in one or two of the older VetInfo Digests on diabetes, so you might want to look through them, too.

Mike Richards, DVM


PZI Insulin and Feline Diabetes

Question: Dear Dr Richards,

I'm in the process of updating a webpage for on current sources for PZI insulin. I've come across the following situation, and I'd like your perspective.

It is apparently true that insulin sold as PZI could be ANY insulin, from ANY source, as long as it's mixed with protamine zinc. So far, I've called around a dozen compounding pharmacies in the US, as well as Blue Ridge Pharmaceuticals, and a pharmacy in England. I was told that absent specific instructions from the vet, when there's a prescription for PZI the insulin source might be any of these (and possibly others): human "Regular" insulin (most common), 100% beef insulin (England), beef-pork insulin (Blue Ridge, its distributors, and a few pharmacists who still have a stockpile or sources), pork only, and SALMON! The pork-only PZI pharmacist I spoke to this morning told me that pork is the closest in structure to cat insulin, and that's why it works. I believe this to be erroneous (I have an article on my desk with a table that says pork is the same as DOG insulin, and is one amino acid different than human insulin. My reading has consistently indicated that bovine insulin is most closely similar to cat insulin.) This pharmacist also told me that she regularly does presentations for veterinary practises, promoting their compounding pharmacy and "educating" them as to the superior efficacy of pork insulin for example. She and several other independent pharmacists told me that while they get their formulas (and medical information) from a consulting agency called Pharmacy Compounding Centers of America, they routinely "improve" on them -- it's entirely at their discretion.

The questions crowding my brain are these:

How is it that you can buy medication that is one thing in one pharmacy and another somewhere else? Where's the regulating body (I need to speak to the FDA, I guess)?

Are vets aware of this? Would they depend on a pharmacist for medical data like which insulin works the best? Are they aware that beef-pork PZI is available? Apparently Blue Ridge is not allowed to advertise, until FDA approval.

Does the source of the insulin matter? All the pharmacists who are using non-beef insulins produce somewhere between 5-100 vials a month, largely if not exclusively for cats. Is the protamine zinc the most important factor in why these animals live on to buy more? Is it the no-more-than-one-injection-per-day crowd that keeps these pharmacists going? Do you know of any science comparing insulins from different sources? I have an old study from eighties showing better curves with PZI than with humulin, but the point was about keeping doses small, avoiding Symogyi, not the insulin source.

I have the impression that you transitioned without trauma to human insulin in your practise, and that you're not particularly anxious to go back to using PZI (beef-pork) now that it's available -- is that so? That seems to be the position of my current vet.

It seems as if we're not all that far from the days when anybody could put anything in a bottle and sell it as a "MMMMMiracle Elixirrrrrrr". Any response to any of this would be appreciated. Thank you.

Laura and Maya (diabetic tabby cat) and Dylan (black cat)

Answer: Laura-

I have to thank you for alerting me to this situation. In my practice, this doesn't affect me much, because I don't use PZI insulin. My reasoning for not using it has nothing to do with the problems you list, though. As you already suspect, it has more to do with the fact that we aren't having too much problem using Humalin H (NPH). Some vets use Humalin L (lente) with about the same success. Online, though, this is very important information and I am gald that you brought up these concerns.

I have pretty much given up on trying to regulate pets on once daily insulin and so I start my patients on twice daily insulin routinely now. I have had good luck with Humalin H (NPH) U100 insulin and it is readily available and will continue to be, which can't be reliably counted on for most other forms of insulin. So I just haven't felt a strong need to find a source of PZI insulin. If I had a patient who didn't do well on NPH insulin I would definitely consider PZI, though.

Anyway, I checked into the situation you outline in your note and found a couple of notes on the Veterinary Information Network advising against using compounded insulins, so I strongly suspect that the situation is about what you describe, but couldn't find specific information to support or refute your findings.

Protamine zinc insulin (PZI) is manufactured by adding protamine sulfide and zinc chloride to regular insulin and then buffering it, according to Dr. Plumb's "Veterinary Drug Handbook". Technically, it probably doesn't matter what the source of the insulin is, as far as the definition goes. Different insulins could definitely affect the patient's response to the insulin, though -- so it would be important to at least insure that the pharmacist always made the PZI insulin exactly the same way.

Beef origin insulin is most closely related to cat insulin. Dog insulin and pig (pork) insulin are identical in structure, so pork was a very good source of insulin for dogs.

The one thing that you have to remember in all of this is that individual cats will often do better on one insulin product than on another. However, the human origin insulins are here to stay and they are currently the only readily available forms of insulin at your local pharmacy. So they are the best products to try first, from a practical standpoint. If they don't work well, then it is reasonable to go on a search for the best insulin for an individual cat.

Thanks again for alerting me to the problems with compounding when it comes to insulin. I do utilize the services of a compounding pharmacy for several products and in general I think they do a good job but it does sound like it is best to rule out compounding as an option for insulin.

Mike Richards, DVM


Diabetes regulation

Question: Dear Dr. Mike,

Our cat Lou was diagnosed with diabetes Jan.1999. He is 10 yrs. old. We have several questions concerning his behavior. At this time we have lost confidence with our vet of 8 years.

History: Lou was drinking large quantities of water with large urine balls in litter.

Jan. 1999. He was always a very large fat cat since 1992 when we adopted him. He weighed approximatly 17 lbs. with a big appetite all the time.After his diagnoses we began giving him insulin Humulin U 2x daily.His blood glucose levels were high 500 +. I verbally talked to Dr. B. over the phone describing the huge urine clumps in the litter. Over a period of 5 months we increased the insulin to 11 units 2x daily.

July 1999 For a few days I noticed something going on with Lou but couldn't pinpoint what it was. He seemed sleepy and not interested in his food. This was very unusal for him. We continued to give him the insulin. I called the vet and discussed my concern. Lou was to go in the following morning for a blood glucose curve. However, my husband Jeff called me at worked to say he rushed Lou to the vet on a emergecy basis. This is where we get concerned about our vet. I'll explain briefly.

Lou had been treated for 6 months by Dr. B. My husband has some medical knowledge since he is a paramedic/ fireman. When Jeff rushed Lou in Dr. R.the senior/owner of the practice took on the case.

Lou was unconscious, posturing with snorring respirations. Dr. R. asked " Could this be trauma?" My husband surprised at the question replied no. Jeff verbally said "You know he is diabetic,right?" Dr. R. nodded. For 20 minutes our cat lay unconcious while Dr. R. took 2 xrays,got a urinalysis.He thought it might be trauma or myocardiohypertrophy before even taking the simple blood test to determine the blood glucose. At that point it was 21 and Lou was hypoglycemic. Our cat was revived but we our upset and question Dr. R's emergency skills.One week later another glucose curve was done and it was determined Lou's levels were normal. We did not give insulin for one month. Looking in hind sight it appears we overdosed our cat while he was spontaneously recovering from diabetes.

After this incident Lou began to rapidly lose weight. We began to do blood curves again. In Sept. his levels were 9am 51112pm 483.8 3pm 443.7 We began 2 unit 1x daily for 2 weeks. A recheck indicated an increase to 2 units 2x daily November 1999 Frutosamin results= 659 blood sugar begin 3 units 2x daily then go to 4u 2x daily

Our cat Lou continued to lose weight to 10lbs. He began urinating and pooping on the carpet.He was constantly looking for food. His behavior was horrible...knocking down milk glasses, in the sink licking plates.Constantly yeowling not meowing. He was put on medication for a bladder infection.

December 1999 Frutosamine results =514 Begin 5u 2x daily

Jan. 1,2000 We leave house for 4 hours to come home and find Lou unconscious again. We rush him to the emerency clinic where they treat him for hypoglycemia.

Jan.7,2000 Thyroid profile sent to Michigan to test for hyperthyroidism Results Neg. Serum Glucose=412

Jan 24,2000 Our vet Dr.B. seems unsure what way to go. We are relieved Lou is not hyperthyroid but do not have a clue why he crashed again. We did not notice any prior symptons.

After reading letters on your website I learned some things. At this time Lou does not have many of the symptoms of the other cats. I suggested trying a new insulin to our vet. He agreed. We have been giving Humilin L 1 unit 2x daily since January.

At first Lou seemed more at peace on the new insulin but as the weeks go by his behavior is getting worse again. Dr. B. wants to wait 3 months before doing another blood glucose. I would like to try 2 or 3 units to see if it helps mellow him out. Dr. B. wants to keep the insulin low and have the blood sugar higher.

Questions. 1) We have lost faith in the senior vet Dr. R. who has treated all our pets since 1992. We wonder if Dr. B. has been treating our cat in a way that is appropriate. Does it appear from my letter these two vets know what they are doing? What key questions do we ask a new vet to know if he has experience treating diabetes?

2) Do other cats act so crazy? Searching for food constantly, meowing all the time with a verascious appetite? Lou's behavoir is very obnoxious now. He will jump on the table to steal food off our plate if we get up and leave the room for 2 minutes. Locking him up in the dog crate helps to keep our sanity but I feel bad.

3) Does 1 unit twice daily seem right? How high could we go knowing Lou has crashed twice in 6 months.

4) The other day Lou got into the dog food and gorged himself. This was around 4 pm. At 6: 30 I fed him and gave him his 1 unit dose. He had been unusually quiet and sleeped all day . I did give him his regular meal and insulin. It took two days for him to get back to his normal obnoxious self. When he eats inbetween meals what happens? Would feeding a midafternoon snack with out insulin be helpful or make things worse?

5) We try to feed him at 6:30 A.M. and 6:30 P.M. However, if we leave at 2:00 to go out for the day and don't come home till we feed early with insulin or wait till we come home? Or can we give 1/2 food and insulin before leaving and give the other 1/2 l later?

Dr. Mike , thankyou for taking the time to read this lengthy letter with questions. What I want most is to see our cat Lou regulated with the correct dosage that makes him feel calm and satisfied. I hate seeing him so agitated and yeowling all the time searching for food all the time. Just a note...Since switching to the new insulin I can tell he has gained weight. He has not been to the vet since January.

Thank you, I look forward to your reply, Beth

Answer: Beth-

I can see why you have concerns.

I am pretty convinced that it is hard to get insulin regulated without doing blood glucose curves to see what the insulin is doing to the pet. I strongly prefer that these curves be done by the owner, using a blood glucometer and blood collected at home, if possible. This is the best way to evaluate the cat in a situation that is closest to the way it really lives, rather than trying to evaluate a stressed out cat who is confined to a cage in our hospital rather than following his daily routine. However, this does mean that the owner has to be able to get a blood sample and it can be hard to do this. We have had the best luck teaching clients to prick the ear vein or artery that runs around the periphery of the ear with a small gauge needle and using the drop of blood produced for testing. At least half our clients can do this.

If you think that you or your husband might be able to do this it should be possible to get a lot better idea about what is actually happening with Lou's blood glucose levels during the day and then to make appropriate adjustments to his insulin. You will need your vet's cooperation in interpreting the lab results and choosing appropriate dosage changes. I don't use Lente (Humulin L Rx) insulin at all, so I am not able to give you any meaningful advice about its use.

Fructosamine levels give an estimate of the overall success of insulin therapy. The levels that you report are high, meaning that the blood sugar is out of normal ranges fairly often in Lou. However, this does not tell you if the insulin dosages are too high or too low. If the insulin dose is too low, then blood sugar stays high. If the insulin levels are too high then the blood sugar drops too low at some point during the day but a rebound effect occurs that drives the blood sugar way up later in the day --- and leads to high fructosamine levels on testing.

Testing the blood every 2 to 4 hours for 12 to 24 hours (most people use 12 to 16 hours but 24 hour testing is a good idea if it isn't too burdensome) gives an idea of whether the insulin dose is too low or too high. If it is too low the blood sugar is above the normal range most of the day and doesn't ever get low. If the insulin dose is too high then the blood sugar is too low part of the day and too high part of the day. If you only test once in a while and happen to hit the high times each time you test, it may seem necessary to keep raising the insulin level even though that is the exact opposite of what should be done. The only way I know to separate these two possibilities is to do serial blood glucose curves.

Once regulation is achieved it may be OK to cut back on testing some but at this point I think it is fairly certain that you have not really achieved good regulation and more frequent testing is necessary.

I use Humulin N (NPH) insulin but ONLY because I used it and had good success with it and kept on using it. I have no reason to doubt that other vets have had similar success using Humulin U (ultralente) or Humulin L (lente) insulin.

I would strongly encourage you to talk with your vet about home testing of blood glucose levels and establishing good glucose curve values for Lou. If your vet isn't willing to discuss this then I really would consider finding another vet. If you find you can't get blood or don't want to try to get blood from Lou, that is a different situation but you still need to figure out a way to monitor and regulate Lou's insulin levels, which will require close cooperation with and trusting your vet. If you don't have that relationship, right now, with your current vets, you still need to find someone you can work with during this time.

Good luck with this. There are some good sites on diabetes in cats. I think we have a link to one of them on our link page or in the text somewhere on the cat diabetes page of our site. If not, I will try to find them again for you.

Mike Richards, DVM


Diabetes - regulating insulin

Question: Hi. My 5 year old Himalayan was just diagnosed with diabetes. He was referred to a specialist and almost died. I fed him 8 to 10 times a day with a syringe and he recovered. He now only weighs 6 lb. and is up to 7 units of insulin per day, taken 2 times. He still drinks and urinates often, has great bowel movements and eats Science Diet dry food as well as low sodium tuna with olive oil and balsamic vinegar. (he loves it and I will give him whatever he wants, at this point). His appetite is fair to good. I have a strong sense of smell and I can smell an acetone odor when his diabetes is out of control.

This happened last week and I thought that maybe the hot weather triggered it. I increased his insulin from 6 to 7 units and he's better. His appetite is back and he is having regular bowel movements. But he is still drinking and urinating too much. What are the signs of too much and too little insulin? I need to get him to gain weight and get regulated and I know that it takes time. Any ideas.

Thank You,

J. K.

Answer: J.K.-

One of the most common mistakes that people make when trying to regulate insulin, early in treating diabetes, is to change the insulin dosage too often. When a change has to be made in the dosage it is best to give it a few days to stabilize the blood sugar before making another change. So part of my advise is to be patient and go a little slow with changes.

Weight gain can take as long as six to eight weeks to occur even in cats that appear to be pretty well regulated on insulin. I am not sure why this takes so long but it often does.

The best way to get a handle on the insulin dosage is to use an at home blood glucose measuring unit (glucometer) and to learn to get blood to test for blood sugar levels. Many of our clients are able to do this and it helps a great deal in getting to the optimal insulin dosages. Most of our clients with cats use the little artery in the ear margin to obtain blood. This can be visualized by shining a flashlight through the ear. A small gauge needle is then used to prick the area directly over this small artery and to obtain blood. This is then put on the glucometer test strip. It really isn't that hard if your cat isn't too bad about being pricked with the needle. Some are and some aren't. If you can get blood in this manner you can then do blood glucose measurements several times over the course of the day and your vet can plot these on a "blood glucose curve" to carefully adjust the insulin dosage.

If you can't get blood then you can always take the glucometer back to the store for a refund (or at least most of the time you can).

The other alternative is to pay really close attention to your cat and to adjust the dosage of insulin accordingly --- along with periodic checks of the blood glucose curve and spot checks of blood sugar in between curves, at your vet's.

If there is excessive drinking, depression, increased or decreased appetite, continued dullness to the haircoat then the insulin dosage probably needs to be increased. This should be done very carefully and with your vet's advice.

If there is normal to decreased drinking, fainting, lack of attention to surroundings, weakness, wobbliness or seizures, then the glucose level is probably too low and sugar should be administered (usually as syrup or cake icing) and a report made to your vet immediately.

The other really important thing is good communication with your vet. Keep talking to him or her about how your cat is doing and try to follow advice that is given, to the best of your ability to do so. It is essential to have a good team relationship with your vet when treating a diabetic patient.

Good luck with this.

Mike Richards, DVM


Conversion factor for units of insulin

Q: Good Morning, Dr. Mike! I am a new subscriber and am looking forward to receiving your newsletter.

Please know that I am what can be considered an "animal fanatic"! I have 2 Russian Blue male cats (from birth litter mates), and find myself the self-appointed neighborhood "watch dog" for the abused and homeless. Money (as always) and space restrictions prevents me temporarily from keeping a house full, but I am determined to find the means to buy my farm & take in only older cats & dogs that need a home! I worked at & now volunteer at our local chapter of the SPCA and would do more if time only allowed.

Jake, one of my "babies" is diabetic - becoming so at the tender age of 11. I have taken this situation very seriously & have spent more money on his health in these past 2 years than I have on my own. I have my local vet, a homeopathic vet in Colorado with whom I consult & purchase supplements from, and I also consult with Dr. Anderson's office in California (the champion of permitting PZI for current use).

I purchase the U40 from Blue Ridge Pharm. who will only sell a minimum of 3 bottles per purchase & who also forces the purchase of a box of 100 ea. U40 syringes per box (it's a long story - if you're interested, I'll be happy to tell you). These syringes are the worst I've run across - dull points - bad rubber stoppers, etc., etc., and I'm please to say that I'm about to use the last of 600. (Jake was on his "honeymoon" for the first part of the year; thus more insulin than syringes).

I've requested conversion factors from the U40 syringe to B-D's No. 328411 1cc syringe from 3 different sources & have received 3 different answers. I have over 2 reams (1000 sheets) of data printed from my internet research on feline diabetes but can find no conversion charts for this.

Can you help me? I will be extremely grateful!

Best Regards,


A: Lyn-

The conversion factor for units of insulin is pretty straightforward, but you still might want to ask your pharmacist when you get U100 syringes, just in case there is something I am missing.

A U40 insulin syringe contains 40units of insulin per 1cc. Since you are going to put the same insulin a syringe that is marked off at 100U per 1cc of insulin, you need to use a conversion factor of 2.5 to give the same units.

So, if you are giving 5 units of U40 insulin but you have to give it using a U100 syringe, then you should give 12.5 Units on the U100 syringe.

The math= 5U x 2.5 = 12.5U

It does seem odd that you SEEM to be giving MORE units but it is easier if you think of it this way: A U40 syringe is a 1cc syringe divided into 40 units, so if the measurement was in cubic centimeters (cc) like a normal syringe, each unit would represent .025 cc. On the other hand, a U100 syringe is just a 1cc syringe divided into 100 units, or 0.01cc per unit.

So, 1 unit of insulin on a U40 syringe = .025cc. Therefore 5 units of insulin = 0.125cc.

But in a U100 syringe, to get 0.125cc you have to use 12.5 Units on the syringe as your measurement because each unit on the syringe equals 0.01cc.

As far as I know, this conversion factor should work with any type of U40 insulin. But that is where you should be cautious and ask the pharmacist, just in case.

Mike Richards, DVM



Q: My cat regulated on ultralente for 1/1/2 yrs. now since june unregulated. am thinking of switching to pzi. supposedly animal based insulin works better on animals? have you heard that? thanks

A: Dear P-

Most of the information below comes from Deborah Greco et al, writing in the Clinics of North America issue "Diabetes Mellitus" (May 1995).

Insulin may come from beef, pork or human sources (through recombinant gene technology). Most veterinarians start pets on human recombinant insulins at this time due to the ease in acquiring these forms of insulin. There are slight variations between the types of insulin, though.

Beef insulin most closely matches cat insulin, of the available types. Pork insulin exactly matches dog insulin in structure. Usually it is possible to use insulin that is not an exact species match without problems but in some cases of insulin resistance it is advantageous to use an insulin that more closely matches the structure of the species of the pet.

Protamine Zinc Insulin (PZI) is currently available again to veterinarians after being off the market for several years. It is a long acting mixture of beef and pork insulin. It was considered to be the best insulin for use in cats prior to the time it was missing from the market, when the goal was once a day insulin injections. As veterinarians switched to other insulin sources, some came to the conclusion that other types of insulin were just as effective or perhaps more effective. At present, NPH insulin is preferred by some of the veterinarians who are considered to be experts in this area.

Regulating insulin dosages can be challenging regardless of the type of insulin used. Past guidelines on insulin use sometimes suggest upper limits of insulin dosing which are no longer considered to be valid guidelines. Before switching types of insulin in a case in which a particular type of insulin was working well it is a good idea to review the history of the insulin use, the cat's lifestyle and environment and to obtain blood glucose curve information (several blood glucose samples drawn over the course of a day and plotted to examine the variations). If a cause for the suspected insulin resistance can be identified it may be possible to re-establish effective control without switching insulin types. It is very hard to achieve good control of blood sugar levels in cats without using twice daily insulin injections. Sometimes veterinarians and clients are working very hard to avoid that necessity but can't achieve control of the diabetes without switching to twice daily injections.

It is very important to maintain really effective communication between yourself and your vet when dealing with a diabetic pet. Diet, stress, poor injection or insulin handling technique, other concurrent diseases, medications and the development of antibodies against the administered insulin are all possible causes of a poor or changing response to insulin dosage. The only way to sort through these possibilities is to review each of them with your vet and to work out a plan to resolve any problems.

Good luck with this. In most cases it is possible to re-establish control of the diabetes even though it can be difficult.

Mike Richards, DVM

Feline diabetes control

Q: I have an 11-yr-old male feline diabetic, Fletcher. He was diagnosed 1/94 and until 1/97 fairly regulated on 7.5 units of Ultralente. We have done blood tests to no avail (ie, no kidney disease, no hypothyroidism, etc.) and only other medical matter was constipation in July, 1996 due to hairballs after which we put him on 1/8th tsp am & pm of Fiberall with food, until 9/96 when we reduced it to evening feed only. However, we have now switched to Iletin Lente (porcine & bovine derived) - any suggestions?

A: I am sorry, but I can't discern what your question is from your note. I am guessing that you are currently having problems regulating the insulin levels? Changing insulin types can help. Giving insulin twice a day instead of once a day can help. If it is possible to induce Fletcher to eat several small meals spaced evenly throughout the day, that helps, too. I know these are general comments that may not be that helpful if you have a more specific question. There is a web site devoted to feline diabetes. I think Michal has put the link on our links page.

Mike Richards, DVM

Diabetes -PZI Insulin is back

Q: Dr. Mike, Thank you most enthusiastically for your thoughtful and detailed response. It's wonderful that you take so much time from your busy day to answer the questions of people you don't even know. Thank you! I understand your disclaimer about the differing opinions of vets and will take that into consideration. Still, just having a second opinion to balance out the first helps me a lot. And your explanation of how diabetes works is terrific! It also helps to have the information in print where I can refer back to it. I am guessing your vet is using Ultralente Iletin 1) insulin. The bottle reads Lilly U-100 R Regular Iletin I. Thanks for the other brands you mentioned. It makes sense to try different insulins if this one isn't working. Mr. Kitty is up to 13 units each morning and it's still not working. It also sounds like twice-daily injections might help. The ideal situation for feeding would be a cat who eats very small amounts very frequently throughout the course of the day, probably. Thanks for this. I hate to see him roaming around so obviously hungry and anxious. :-) Thank you SO MUCH for your letter and your obvious love of animals. Kimberly

A: Kimberly- In case your vet misses the announcement (I just saw it by accident), PZI insulin has been approved by the FDA under the compassionate need rules and should be available as an "experimental drug". It was considered the most successful insulin for use in cats and has been sorely missed by veterinarians since it disappeared from the market several years ago. It would be good to consider this option if you are still having problems with insulin regulation.

Mike Richards, DVM

Insulin and Rezulin

Q: My vet and I have had difficulty regulating my Missy (13 yrs old) on Insulin. He has been trying different Insulins because Missy appears to be resisting Insulin in general. Her blood sugars continue to run into the 600+ even with large Insulin dosage. Have you heard of the drug "Rezulin" and whether or not anyone has tried it on felines. I discovered it on the Internet and told my vet I was willing to try it as an expermental treatment. However, there doesn't seem to be a lot of info on cats using it. Thanks, M.

A: Troglitazone (Rezulin Rx) is a new medication that shows some promise in humans suffering from insulin resistance. Since this is a problem in cats, as well, it seem likely that the medication might help. Unfortunately, I can not find any information suggesting that anyone has actually tried to do this or that a dose range for the medication has been established. It is reported to have a pretty wide safety margin in people so if you and your vet decide to try to use it I hope that works to your benefit.

Good luck with this. Cats can be incredibly difficult to regulate on insulin at times and it would be nice if an alternative was discovered.

Mike Richards, DVM


Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...