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Updated November 14, 2022 – Nearly 100 years ago, a team of Canadian medical doctors made an astonishing finding – a hormone responsible for blood sugar regulation. Before the discovery of insulin, diabetes was feared and fatal – an untreatable group of diseases that caused sugar dysregulation with cascading health consequences. The discovery of insulin revolutionized the treatment of diabetes mellitus in people, and within two years of its discovery insulin was available worldwide, saving countless lives.

People weren’t the only ones benefiting from the discovery of insulin. References to treating diabetes in dogs go back to the 1940s and treatment options for both dogs and cats have advanced significantly in the last two decades. Insulin has been, and remains, a cornerstone of diabetes therapy for both species.

A Growing Problem
Diabetes is an important disease in dogs and cats. Banfield Pet Hospitals reported in 2016 that diabetes diagnosed in their hospitals increased by just under 80% from 2006 and 2015. The prevalence in cats increased 18% in the same time frame, but the prevalence in cats overall is much higher than dogs. The bottom line is that diabetes is a common and growing problem in our pets. Since insulin therapy is a key part of treatment of diabetes in pets, it's important pet owners know the latest facts about insulin use in pets.

Early insulin preparations were made as extracts derived from pork and beef pancreas. Today, commercially produced recombinant human insulin is the dominant form of insulin available and is the primary type of insulin used to treat both dogs and cats with diabetes.

Unlike people, who get type 1 or type 2 diabetes, the disease in dogs defies easy classification. In cats, the picture might be a bit clearer, since diabetes in cats shares similarities with type 2 diabetes in people. An important distinction that differs between diabetic dogs and cats and diabetic people is that the oral medications often used to treat diabetes in people have had disappointing results when used in pets.

Insulin Treatment
If you have a pet with diabetes, or have diabetes yourself, you know there are many different types of insulin preparations. Sorting through all the options available can be daunting, especially as newer types of insulin are released and older forms are either modified or taken off the market.

In general, insulin is divided into four different types based on three characteristics:

  1. How quickly the insulin begins to work once it is injected
  2. The time to peak insulin action
  3. How long the insulin lasts

Insulin types based on characteristics:

  1. Rapid-acting insulins start to work within 15 minutes of injection. Activity peaks in one hour and lasts two to four hours.
  2. Regular, or short-acting, insulins start to work around 30 minutes after injection, and their activity peaks two to three hours later. These insulins last anywhere from three to six hours.
  3. Intermediate-acting insulins take two to four hours to start working. They reach peak activity in four to 12 hours, and last approximately 12 to 18 hours.
  4. Long-acting insulins take several hours to reach the bloodstream but don’t have a peak in activity. They last 20 to 26 hours.
  5. Ultra-long-acting insulin – this new category of insulins is currently under study for use in dogs. Possibly only one injection per week is necessary. Research in cats lags behind but is ongoing.

Other less common forms of insulin include mixtures of different types of insulin, and insulins of different concentrations.

Insulin is manufactured in different concentrations, and insulin concentration is measured as units of insulin per milliliter of fluid. The most common forms used in veterinary medicine are U-40 (40 units of insulin per milliliter) and U-100 (100 units of insulin per milliliter). Insulin syringes are calibrated for each type of insulin, making insulin measurement easy, but it is critical the correct type of insulin syringe is used.

Although giving your pet injections can seem daunting, the majority of pet owners quickly master the technique. Insulin therapy coupled with proper diet and exercise allows dogs and cats with diabetes to lead long, healthy lives.

Morris Animal Foundation is committed to improving the lives of our furry friends through animal health research. Check out our latest studies and learn what you can do to join us to improve the lives of dogs and cats worldwide.