Diabetes Mellitus in Dogs and Cats

Cat licking dog's face

About one of every 300 dogs and one of every 230 cats will develop diabetes mellitus during his or her lifetime. The disease can develop at any age, but most diabetic dogs are diagnosed between ages 7 and 10. Most diagnosed diabetic cats are older than 6. Obesity is a significant risk factor.

Diabetes mellitus is caused by the body’s inability to use its cells’ main source of energy—glucose—normally. 

Insulin, a hormone produced by the pancreas to help regulate blood glucose levels, plays an essential role in transferring glucose from the bloodstream to the cells. In diabetics, the pancreas may not produce enough insulin, or the sensitivity to insulin may be impaired. 

As a result, the cells do not receive enough energy to function properly.

Blood glucose levels that are too high or too low can be life threatening, but with prompt diagnosis and ongoing management by the veterinary team in collaboration with the pet owner, most diabetic pets can live long, healthy lives. 

What to Look For

Symptoms of diabetes mellitus include—

  • Excessive water drinking and increased urination
  • Changes in appetite
  • Weight loss
  • Cloudy eyes, especially in dogs
  • Chronic or recurring infections

If your pet is showing any of these symptoms, contact us to schedule an appointment for an examination right away.

We confirm the diabetes diagnosis by checking glucose levels in your pet’s blood and urine. We may also run additional blood and urine tests to rule out other medical problems common to older pets. 


Once we make the diabetes mellitus diagnosis, we will most likely prescribe twice-daily insulin injections, showing you how to give the shots at home. Most pets tolerate the injections well. 

We may also recommend changes to your pet’s diet and prescribe a program of daily exercise suitable for your pet’s age, weight and overall physical condition.

To monitor your pet’s blood glucose levels—more frequently at first, as we adjust the insulin dosage, and then about every six months—we will prescribe a FreeStyle Libre 14-day Continuous Glucose Monitoring System. For more information about FreeStyle Libre, see our post titled “Better Care for Diabetic Pets.”

For detailed information about how the FreeStyle Libre system works, you may review and download our handout, “Continuous Glucose Monitoring for Your Diabetic Pet Using the FreeStyle Libre 14-Day CGM System.”

For more information about diabetes mellitus in pets, visit the American Veterinary Medical Association’s website.