Wednesday, March 12, 2014

What's the Best Insulin for Treating Dogs with Diabetes Mellitus?

I am writing you regarding my 11-year old male Weimaraner, Duke. He has always been in good health but over this past week he has had 2 ”accidents” where he has urinated in the bed. He has also been drinking a lot more water than usual and urinating more too.

I  took him to the vet because I had a feeling he might be diabetic. My veterinarian confirmed that it was indeed diabetes mellitus and started him on 10 units of NPH, once after breakfast and once after dinner.  He has improved since starting the insulin, but remains quite thirsty and continues to urinate excessively.

Now I know that this will not give very good control alone because NPH is only a long-acting insulin. I am a Type 1 diabetic, diagnosed when I was 12 years old, so I have quite a bit of experience dealing with this disease. I want my poor puppy to be as controlled as possible so he does not feel like I do when my sugars are out of control— lethargic, nausea, headaches, unquenchable thirst, urinating all the time, and just plain crappy! Not to mention the stress this puts on the on the rest of the body.

If dogs are anything like people, I believe that Duke needs an insulin mixture that will bring his blood glucose down to normal and keep it leveled out. I have been giving him the rapid-acting insulin analog Humalog (insulin lispro) along with the NPH and that seems to be working really well, with marked improvement in his thirst and urination.  The only problem is that he needs 4-6 injections of Humalog each day. I was hoping you have had experience with something that would give him the same control as Humalog but with less injections daily.

In the past, I have used short-acting Regular insulin (before Humalog was invented) but I do not remember how the dosing went. I do have much better control with the Humalog but I am also on an insulin pump, so NPH insulin is no longer necessary.

Any help you can give to allow my dog Duke better control long term without so many injections would be greatly appreciated.

My Response:

In dogs, veterinarians commonly start with an intermediate-acting insulin (NPH or Vetsulin) twice a day (1,2). In some dogs, I find it necessary to add a short-acting insulin to the longer-acting insulin preparation, but many dogs can achieve adequate glucose control without giving more than 2 injections per day.

Insulin of choice for canine diabetics
In my opinion, the insulin of choice for most dogs is Vetsulin (porcine insulin zinc suspension; Merck Animal Health) (3). The main advantage of Vetsulin (known as Caninsulin outside the USA (4), is that it is actually composed of both short- and long-acting insulin components (see Figure below, showing the duel peaks of activity) (5,6). So giving Vetsulin is like administrating NPH together with a second, short-acting insulin preparation, like you are doing now.  However, Vetsulin works better than NPH for most dogs because it has a longer duration of action than NPH.

Timing of meals and insulin injection
The short-acting amorphous fraction of the Vetsulin, which composes 35% of the insulin activity, acts like regular insulin or Humulog, mainly to control the rise in blood glucose after each meal (6).  To help prevent severe rises in glucose after meals, however, it is also important to give the insulin before meals, instead of after the food is ingested, as you are doing now. This protocol will allow the short-acting insulin to be absorbed into the blood stream and ready to act to lower the blood sugar as soon as the food is absorbed from the gastrointestinal tract (7).

The only time I don't do this insulin-feeding protocol is in dogs that don't always eat their meal well; but even in those dogs, I never wait long after the meal is finished to give the insulin. Instead, I always give the insulin injection as soon as possible, once the dog has eaten a sufficient amount of food.

Vetsulin (porcine insulin zinc suspension), with it's 2 peaks of insulin activity


  1. Nelson RW. Canine diabetes mellitus In: Ettinger SJ, Feldman EC, eds. Textbook of Veterinary Internal Medicine: Diseases of the Dog and Cat. Seventh Edition ed. St. Louis: Saunders Elsevier, 2010;1449-1474.
  2. Davison LJ. Canine diabetes mellitus In: Mooney CT, Peterson ME, eds. BSAVA Manual of Canine and Feline Endocrinology. Fourth ed. Quedgeley, Gloucester: British Small Animal Veterinary Association, 2012;116-132.
  3. Vetsulin website. 
  4. Caninsulin website.
  5. Monroe WE, Laxton D, Fallin EA, et al. Efficacy and safety of a purified porcine insulin zinc suspension for managing diabetes mellitus in dogs. J Vet Intern Med 2005;19:675-682.
  6. Fleeman LM, Rand JS, Morton JM. Pharmacokinetics and pharmacodynamics of porcine insulin zinc suspension in eight diabetic dogs. Vet Rec 2009;164:232-237.
  7. Cobry E, McFann K, Messer L, et al. Timing of meal insulin boluses to achieve optimal postprandial glycemic control in patients with type 1 diabetes. Diabetes Technol Ther 2010;12:173-177. 


amandaflips8842 said...

Dr. Peterson,
Thank you so much for your quick response, it is truly appreciated. I will speak to my vet about the Vetsulin for Duke, maybe that will be a better choice for him/us.
I hope this helps someone else as well, as there is not very much info online about all of this.
I do wish we were closer to your Clinic so we could bring Duke, you sound like you truly care about the animals you treat as well as their owners.
Thank you again for taking the time to respond to my inquiry.
Amanda Washington~

Craig Michelson said...

I believe many of us who started on Vetsulin years ago, but were forced to NPH when Vetsulin was removed from the U.S. market, have remained on NPH for financial reasons. A 400 iu vial of Vetsulin costs about $50-60, where the Walmart ReliOn contracted Novolin-N is $25 for 1000 iu. Much less expensive! Plus the standard U-100 syringes are less expensive than the U-40 syringes used with Vetsulin.

I do mix a tiny amount of Novolin-R with the Novolin-N to head off the post meal blood glucose rise.

Craig ("dad" to 6+ year diabetic Annie)

Dr. Mark E. Peterson said...

The cost of Vetsulin is around $25 a vial, so that means that your vet is doubling the price of a vial, which is a common practice. But when you now buy the NPH directly from Walmart, the vet makes nothing so that price increase doesn't make much sense to me. But again, I'm probably not much of a businessman!

In any case, the reason that I like Vetsulin over NPH or even NPH/Regular mixtures is that the "ultralente" portion of Vetsulin lasts much longer than NPH (and therefore is more effective) in most diabetic dogs. But if the NPH is working well for you and your dog, then use it!

You can buy premixes 70/30 vials of NPH/Regular at Walmart for the same price if you don't want to give 2 injections or do the mixing yourself.

Diane M said...

My dog was not doing well on Vetsulin. Her readings were always over 300. Just switched to 70/30. She is 13.2 pounds & I'm giving her 6 units so far the same response, start out at 300 goes down to 200. After 6 hrs starts rising, ending with readings between 300-400. Please help.

Dr. Mark E. Peterson said...

You and your veterinarian need to figure out what's causing this resistance to both of the insulins. I am not going to be able to help you in a couple of sentences, but the solution isn't in continuing to switch insulins but to find out what's wrong with your dog. Have they done a complete urinalysis with culture? If not, that should be done.

If your vet doesn't know what to do, then request a referral to an internal medicine specialist.

Amy Reimer said...

Dr. Peterson,
I'm wondering also if you'd know anything about dosing for the 70/30 Walmart insulin. I believe our vet figured vetsulin at .5 mg/kg twice daily and he seems to be doing well with that dose so far but we'd like to get the cost down if possible. Any resources you have available to share would be greatly appreciated.

Dr. Mark E. Peterson said...

The Walmart 70/30 insulin may work fine. See this post:

But you will have to redo the diabetic regulation and it might not last as long as the Vetsulin.


Our 11 year old cairn terrier Lola has been on Humulin N NPH insulin for 90 days and seems to be doing well. The pharmacist suggested we switch to Novolin which is much less expensive. What are the risks of doing this? Is there any difference in how they work?

Dr. Mark E. Peterson said...

Both are NPH insulins but they may act differently in the individual dog. So I'd monitor carefully for hyper- or hypoglycemia after you switch. Talk to your veterinarian.

JSP said...

My 7 year old (152 lb) Great Dane was started on 35 units of Vestulin BID two weeks ago. He had a glucose curve performed yesterday with poor results. Pre-curve glucose was 465. He was fed and then administered his regular dosage with glucose checks performed hourly thereafter. The results were 576, 598, 642, 618, 619, 523, 621 and 593. The vet increased him conservatively to 40 units.

I'm interested in your comment regarding giving insulin before feeding to allow short-acting insulin absorption into the blood stream prior to food absorption in the GI tract. How long before feeding is an optimal time to give an injection? Our dog is not overweight (and is actually losing weight). He isn't endanger of not eating, so is a candidate for this approach.

Thanks for any insight you can provide.

Dr. Mark E. Peterson said...

I give the insulin 30-60 min before each meal, both morning and evening.

Craig Michelson said...

JSP: WOW, that is a big puppy! :-)

I would highly suggest you consider / talk with your vet about switching to Novolin-N from Walmart. As I mentioned on 3-12-14 above, Novolin-N from Walmart is only $25 for a 1000 unit vial. You would get 12 days out of the vial of Novolin-N instead of the 5 days you will get from the vial of Vetsulin. If you are paying $50-60 for Vetsulin, the switch to Novolin-N from Walmart would save you BIG $$$

One thing you must know is that you would need to switch to different (U-100) syringes with Novolin-N (IMPORTANT). The good thing is that U-100 syringes can also be purchased at Walmart for less than the U-40 syringes you are currently using with Vetsulin.

I would think your vet would have mentioned this because your usage of Vetsulin is so expensive!

Craig Michelson said...

You might want to look at k9diabetes(dot)com for fellowship and general discussions about diabetes with our "kids". There is a very active forum associated with k9diabetes(dot)com.

(Hope this plug is OK with Dr Peterson)

Unknown said...

Where and can I get and insulin pump for my dog? She's a 8 yrs old. She was diagnosed with diabeties in March this year. She is finally in a good range with her gloucose levels. I'm very interested in insulin pump. I've read studies about it but need to know if my dog is a candidate and who performs the surger

Dr. Mark E. Peterson said...

Talk to your vet about a specialist that does work with continuous glucose monitoring systems. These are not used for treatment but rather for monitoring glucose to determine the correct or best insulin dosage, type, and dosing protocol.

Dr. Mark E. Peterson said...

Yes to both questions-- give the insulin before the meal is better and lowering the dose when you make this change is a good idea, together with your blood glucose monitoring.

Good luck!

JSP said...

An update to our situation. Our Dane is not responding well to Vetsulin IMO. I performed a glucose curve on him at home after one week of being on a 40 unit twice daily dose resulting in the typical dual peak graph. However, his range was still between low 400s and mid 600s. Given these results, the vet increased him to 45 units twice daily. He has been on that dose for a week and I am doing another curve. The resulting graph is looking like the insulin resistance graph shown on the Vetsulin website. His values are relatively flat ranging between 497 and 593. He is losing weight with rib and hip bones becoming more prominent. I'm questioning if he has something else going on at this point or if we need to try a different insulin. At first, I thought his dose was not high enough, but with these last results, I just don't know. I am actively working with his vet, but any additional insight is appreciated.


Dr. Mark E. Peterson said...

I can't tell you if something else is going on .. you have to speak to your vet about that. I'd consider to change in insulin to detemir (Levemir). That is much more potent than Vetsulin in dogs (initial dose, 0.1 U/kg, twice daily). See my other posts about that insulin.

JSP said...

Thanks for your feedback. I will read your posts and other information I can find about Levemir.

randy yates said...

Dr. Peterson, I had left a post on the vetoryl blog and while doing some reading I ran across this site for canine diabetes. Wanted to follow up with my concern. My Maltese, Mimi is currently 15 lbs and was diagnosed with cushings about 2 months ago. After about 4 stim tests and increasing her vetoryl dosage to 10 mg twice daily she has recently developed diabetes. Her last test yesterday revealed her blood glucose level was 480. We started her on .4 vetsulin twice daily. Her pre stim test has been 2.5 for the past 3 tests but her post was 10 and on last one gone up to 13. My concern is where did the diabetes appear from and did that affect the increase in her post test numbers going up slightly. I was expecting with increasing the vetoryl from 5mg to 10 mg twice daily that her numbers would continue to come down. They went up 3 on post test and now she is diabetic. We are considering increasing to 15 mg twice daily while trying to get glucose down as well. Could I have your opinion? Thanks, Randy

Dr. Mark E. Peterson said...

Obviously the Vetoryl isn't working so well. I'd recommend switching to mitotane (Lysodren) to get the Cushing's quickly under control. Talk to your vet.

KristinG said...

Dr. Peterson, thank you for the information posted. I have a newly diagnosed diabetic dog (4 months). Our current vet has started her on ProZinc - currently 10 units 2x/day. Her glucose levels are still fairly high (recent readings of 285-400). My question is in regards to the various types of insulin. My understanding is that for dogs, there is NPH (Humulin/Novolin), Vetsulin, or Lantus/Glargine. I'm not sure why our vet recommended ProZinc (I have heard it is formulated for cats), but is your recommendation still for Vetsulin? I thought it had been taken off the market? In addition to being fairly expensive, I'm not comfortable with her on the ProZinc and would like to move her to a different insulin. Thank you for your opinion.

Dr. Mark E. Peterson said...

ProZinc does not work well in most dogs and is very expensive. Yes, I'd go with Vetsulin, which has been back on the market for a couple of years.

None said...

What brand of dog food do you recommend for a diabetic dog (toy Manchester Terrier 15#)?

Dr. Mark E. Peterson said...

No preference. Just be consistent with amount of food fed and timing of meals.

None said...

Thank you for the prompt response! We really like our vet but it seems he has limited experience treating diabetes. Is there a resource for locating an endocrinologist in our area (TN/GA)? Also, is anyone treating canine diabetes with stem cells?

Dr. Mark E. Peterson said...

I would contact the American College of Veterinary Medicine (ACVIM) or the state Veterinary Schools for a specilist

DebL. said...

My mini pin developed diabetes, her blood sugars were in the 600s. The vet recommended we put her on a high fiber WD dog food for diabetics as well as vetsulin. She has lost weight and is feeling so much better. It's like we have a puppy again.

MWP48 said...

Dr Peterson
My lab-beagle mix was on Novalin from Walmart and we tried it for several weeks and increase the dosage up to 15 units bid and the sugar on several curves was staying around 600. We have him on a diabetic diet with diabetic food. Our Vet switched us to Vetsulin and we started at 9 units bid and now up to 18 units bid and the glucose curve every three hours is 516 500, 606. Any suggestions would be appreciated. Someone said that cinnamon may help regulate diabetes. If you agree how much do you give him if he weighs 58 lbs.

Dr. Mark E. Peterson said...

You need to rule out common problems with insulin "resistance". I'd start with a complete urinalysis and culture since many of these dogs have underlying urinary tract infections. Talk to your vet.