Diabetes Mellitus in Cats

What is Diabetes Mellitus
Diabetes Mellitus is caused by deficient production of insulin in the body. Insulin is a hormone produced by the pancreas that works to control blood sugar levels. When there is not enough insulin, blood levels of glucose become too high, allowing sugar to pour into the urine. It produces the clinical signs we see at home.

Why is Glucose Important?
Glucose provides the cells of the body the energy they require to perform a variety of different jobs. It can enter cells with the help of insulin – insulin opens the “door” to allow glucose to enter. Without insulin, glucose is locked out of cells and unable to provide the energy your cat’s body needs to work.

What Does a Cat with Diabetes Look Like?
Diabetes is a common endocrine disease seen in middle-aged to older cats. The main signs to watch for would be:

  • Increased drinking
  • Increased urination
  • Weight loss
  • Increased appetite

If your cat exhibits any or all of these signs, please bring them in to see your veterinarian.

How Does My Vet Diagnose Diabetes?
Once you bring your cat to the vet, your veterinarian will perform a full physical exam, including checking his or her weight. It would be the first clue that something might not be right. The next step is to run a blood test to look for an elevated level of blood glucose as well as a urine sample to see if there is glucose in the urine. An additional test, called fructosamine, measures your cat’s blood glucose level over approximately two weeks – this is often used to confirm the diagnosis of diabetes.

  1. Elevated Blood Glucose
  2. Glucose present in the urine
  3. Elevated Fructosamine
  4. Consistent clinical signs

My Cat has Diabetes – Now What?
Once your cat has been diagnosed with diabetes, there are two very important treatments to begin

  1. Insulin Therapy: Your veterinarian will prescribe a specific type of insulin for your cat, which they will need to receive injections of twice daily (sometimes once daily). While giving injections to your cat may sound scary, most cats tolerate it very well, and owners develop a strong sense of confidence as treatment goes on. It is important your cat receives insulin according to the instructions provided by your veterinarian. Your veterinarian or registered veterinary technician will schedule a time to teach you how to administer insulin at home safely. Insulin is always administered following a meal – if your cat does not eat, then do not administer insulin.
  2. Diet Therapy: What food your cat eats is almost as important as insulin treatment. It is highly recommended to transition your cat onto a diabetic friendly diet that is low in carbohydrates and high in protein. Canned food is often the ideal selection for diabetic cats. There are veterinary therapeutic diets available specifically for cats with diabetes that can be purchased from your veterinary hospital. Obesity predisposes cats to develop diabetes but also makes it much more difficult for getting their insulin dose and blood glucose levels under control. Your veterinarian will help develop a diet protocol to help keep the unhealthy weight off of your cat.

Monitoring at Home
Once your cat has been started on insulin, their blood glucose levels will need to be monitored to ensure the dose of insulin is working for them. To reduce stress on your cat, a glucometer (blood sugar measuring device) can be purchased for you to measure your cat’s blood glucose level at home. A registered veterinary technician can teach you how to use the machine as well as how to collect a very small blood sample from your cat.

The other important thing to monitor at home is whether your cat begins to drink and urinate less – this is a good indication that insulin therapy is working. If you feel your cat is drinking or urinating more, then please contact your veterinarian.

Hypoglycemia is when blood sugar levels are too low – this can be a medical emergency. Signs to watch out for include

  • Weakness
  • Ataxia
  • Collapse
  • Seizures
  • Disorientation
  • Mental dullness

If you notice any of these signs in your cat, do not administer insulin and call your veterinarian immediately.

Additional Health Requirements
Diabetic cats release glucose into their urine – this glucose acts as food for bacteria that live within the urinary tract. Why is this important? Diabetic cats are at an increased risk of developing urinary tract infections, so it is important that they routinely have their urine assessed. Other important conditions that need to be dealt with include kidney disease, dental disease and heart disease.

Diabetic Remission
Cats are incredible animals in so many ways, but one of the most remarkable is that they can respond so well to insulin therapy that they no longer require it. With appropriate and timely treatment (diet and insulin), some cats will improve their pancreas ability to produce insulin on its own. These cats should remain on a therapeutic diet that is low in carbohydrates and high in protein. Biannual health checks with a veterinarian to monitor their diabetic remission status will also be essential.

If you have any questions, please give us a call at 416.537.3128.

Written by: Dr. Leah Kahn, DVM



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Our veterinarians are currently seeing all patients by appointment ONLY.  We continue to operate with a "closed waiting room" in order to keep our clients and staff safe during the pandemic. We appreciate your patience and understanding as these appointments take a little longer than normal.  

How do appointments work?
Please come to the back door for your appointment and call 416-537-3128 upon arrival. A veterinarian will speak with you over the phone and a veterinary assistant will come out to collect your pet for an examination. After examining your pet, the doctor will follow-up on the phone with their findings and recommendations. Thank you for entrusting us with the care of your pets. Please let us know in advance if they have any special needs.
Payment Methods:
We are currently accepting all payment methods. However, credit or debit cards are preferred.
How to collect food and prescription orders:
We appreciate advance notice for food and prescription refills. Please call 416-537-3128 upon arrival at the FRONT DOOR and a receptionist will be out with your order as soon as possible. For faster service, we suggest ordering pet supplies and food through our online store.  Delivery is free with purchases over $100.00.  It's easy!  Just click ONLINE STORE on our website to sign up.


Thank you for your patience and understanding and we look forward to seeing you and your furry family members again!

- The team at Annex Animal Hospital