This week I had a client ask how to change her pet from one type of insulin to another, and if she could do it during her upcoming vacation.

Before you make the choice to change (which can be an expensive endeavor), we want to make sure you are making the most of the insulin you are currently using. Are you giving it as directed by your vet? Are you feeding as directed, or is someone in the family sneaking lots of inappropriate or mid-meal snacks? Has your vet watched your technique of drawing up the appropriate amount and injecting the insulin into your pet? Are you changing vials of insulin as directed by your vet, or has it gone expired? If you have a cat, are you feeding low carbohydrate (canned only) food? These are basic questions to consider before switching to a new type of insulin. After all, it’s not just a new vial/pen of insulin you will need to purchase. You will likely have to change syringes as well. It’s financially costly and can take time to find the right dose of the new insulin. If you are disregarding basic suggestions and haven’t achieved glucose regulation, changing to a new insulin without adhering to your vet’s recommendations may make no difference at all.

Why would you change? In general, if we achieve most of the blood glucose values under 300 mg/dl we probably won’t see the clinical signs of diabetes that affect a pet’s quality of life. Heck, a pet drinking and peeing excessively affects the pet owner’s quality of life, too! My “big picture” goal for a diabetic pet is to have most of the numbers of a glucose curve to be under 300, and to have the curve bottom out somewhere around 100. A glucose curve tells us how long the insulin lasts in a particular pet. It also tells us if we can safely increase the dose. For example, if the curve bottoms out at say 50 mg/dl, we cannot increase the dose and should actually decrease the dose a bit. Running blood glucose curves and sharing the results with your veterinarian is the best way to determine the best dose for your pet. On occasion, your vet may opt to change to a different insulin.

Sneak up on that dose! Whether I am starting a newly diagnosed diabetic on insulin for the first time, or whether I am changing a pet already on insulin to another type of insulin, I start at the low end of the dosing recommendation for that type of insulin. Some pets will need more insulin and some pets will require less insulin. And some insulins are more potent than other insulins. We don’t know the magic dose until we try it in a pet. If we start at a dose that is too high for a particular pet, the blood glucose may drop too low and the liver will respond by making glucose. This is called the Somogyi swing and can be extremely confusing. It can be downright hard to identify the Somogyi swing, too! If we start low and gradually increase the dose we are less likely to encounter this phenomenon. It is best to start low, run a blood glucose curve in 5 to 7 days, then re-evaluate the dose.

As always, I enjoy hearing from our readers and clients. You can email me at Joi.SuttonDVM@adwdiabetes.com. I get a lot of our article topics from questions by readers.


NOTE: Consult your veterinarian to confirm that my recommendations are applicable for the health needs of your pet.

Dr . Joi Sutton

Dr . Joi Sutton

Dr. Joi Sutton is a 1993 graduate from Oregon State University. She has practiced both in emergency medicine and general practice. Dr. Sutton has done extensive international volunteer work and is the President and Founder of Veterinary Ventures, a nonprofit organization that takes teams of veterinarians to undeveloped countries for humane medical care. She also runs a small animal practice in South Florida.
Dr . Joi Sutton