What is diabetes mellitus (DM)?
First, a quick overview – bear with us. The word diabetes comes from ancient Greek and means siphon, or running through (referring to the large volume of urine) and mellitus is Latin for sweet. The disease is appropriately named because diabetics are siphons for sweet urine. DM in animals works the same way as it does in humans. When you eat a meal, carbohydrates and sugars passing through your gut get absorbed to your bloodstream in the form of glucose.

Insulin is a hormone which signals your body to move glucose from your blood into muscles and organs to be either used for energy right away or stored for later use. In diabetic animals, insulin is either not present or not doing its job. This leaves too much glucose in the blood, where it can’t be used. Hyperglycemia is the specific word used to describe having too much glucose in the blood. It is normal for an animal to be hyperglycemic right after a meal, especially one high in carbohydrates, but diabetes is characterized by “persistent fasting hyperglycemia.” An animal who is persistently hyperglycemic would have too much glucose in their blood regardless of when they last ate a meal. The blood glucose levels will get so high that glucose leaves in large quantities through the urine – hence sweet siphon – Diabetes mellitus.

How do I know if my animal has diabetes?
The three cardinal signs of diabetes in our furry friends are

  • Increased drinking
  • Increased urine output
  • Increased eating without weight gain

These symptoms alone are not enough to diagnose diabetes. Bloodwork and urine tests will confirm the disease. If this list sounds like your animal at home, bring them into your local veterinarian. Pets will lose weight over time if the diabetes is not controlled. Some dogs can suddenly develop bright white cataracts and lose vision.

How do we treat Diabetes Mellitus?
Treating diabetes is a team effort, and you as the owner will be the most important member of that team! Insulin and diet modification are the mainstay of treatment. There are many different types of insulin which work in unique ways. Your veterinarian will develop a plan specific to your animal, but you are the one who will be carrying out this plan. In general, a diabetic food will have less simple carbohydrates to prevent a big spike in blood glucose after a meal. You will also perform once or twice daily insulin injections. Don’t worry! You do not need to be a trained nurse to do this correctly. The needle is super small, and your pet will hardly feel the poke. Your vet team will show you how to do this when your animal is diagnosed.

How do I know that the treatment plan is working?
The goal of treating diabetes is to avoid the clinical signs (increased drinking, urination, eating) while avoiding hypoglycemia (dangerously low levels of blood glucose). It may take a couple months to get there as we get used to the new diet and find the appropriate insulin type and dose. At home monitoring is very important in this process!

I would encourage every owner of a diabetic pet to keep a daily log of appetite, thirst (increased or decreased) and insulin dose. This is especially important for newly diagnosed and geriatric animals. Lucky for you (and us!), there are many innovative ways to monitor your pet’s diabetes from home. You can buy a litter additive that will change color if your cat is shedding glucose in the urine. Another great new monitoring tool is the FreeStyle Libre blood glucose monitor. For up to 14 days, your pet will have a tiny probe under its skin, continuously sampling the glucose. You will scan the patch with your phone every 8 hours or so and an app will send that data right to your vet! This product was originally developed for humans, so we know that the probe size and placement are not bothersome for everyday life.

To summarize… a well-controlled diabetic will have a stable weight, and eat, drink and pee a normal amount.

Quick note on HYPOglycemia…
Hypoglycemia is a term that describes too little glucose in the blood. Animals are much better at tolerating HYPERglycemia than they are hypoglycemia. They can live for quite some time with too much glucose in the blood, but too little can get dangerous quickly. Watch for general weakness, collapsing, trembling, and/or seizures. If you see any of these signs, rub honey or corn syrup on your pet’s gums and call your vet immediately. Accidental insulin overdose can cause this sort of hypoglycemic shock.

Peter Jorgensen – Iowa State University DVM Candidate ’25