Updated September 25, 2026. Fact-checked against veterinary sources; review by a licensed veterinarian is in progress. See our editorial policy.
Quick answer: Diabetes mellitus is most common in middle-aged and older dogs. Classic signs are drinking and urinating more, weight loss despite a good appetite, and sometimes sudden cloudy eyes from cataracts. Nearly all diabetic dogs need insulin injections, usually twice a day with meals. Oral diabetes pills used in people don’t work well for dogs. With consistent insulin, feeding, and monitoring, many diabetic dogs live good lives for years.
This guide doesn’t give insulin doses. Your vet will set and adjust your dog’s dose.
Signs
- Increased thirst and urination, including accidents
- Increased appetite with weight loss
- Lethargy
- Cloudy eyes or sudden vision loss (cataracts)
- Recurring urinary tract or skin infections
Emergency: diabetic ketoacidosis (DKA)
See a vet immediately if a diabetic or possibly diabetic dog has vomiting, won’t eat, is very weak, breathes fast, or has breath that smells sweet or like nail polish remover. DKA is life-threatening.
Diagnosis
Your vet will find persistently high blood sugar and sugar in the urine. Additional tests look for problems that make diabetes harder to control, such as urinary infections, pancreatitis, and Cushing’s disease.
Treatment
- Insulin injections, usually twice daily, given right after a meal. Veterinary insulin products (such as porcine lente or protamine zinc insulin) and some human insulins are used.
- Consistent diet: the same food, amount, and timing each day. Your vet may recommend a diet with moderate fiber.
- Weight management for overweight dogs.
- Spaying intact females, since heat cycles cause hormone changes that interfere with insulin.
- Treating other conditions like infections or Cushing’s disease.
Insulin safety
- Match the syringe to the insulin: U-40 insulin needs U-40 syringes, and U-100 needs U-100 syringes. Mixing them up causes major dosing errors. Insulin pens are also an option.
- Follow the product’s mixing instructions: some insulins are shaken, others gently rolled.
- Store insulin as the label directs, usually refrigerated.
- If your dog doesn’t eat, call your vet before giving insulin. They may advise a reduced dose or skipping it.
- If you’re unsure whether a dose was given, don’t give another. Skip to the next scheduled dose. A missed dose is much safer than a double dose.
Low blood sugar (hypoglycemia)
Signs include weakness, wobbliness, trembling, confusion, and seizures. If your dog is conscious and able to swallow, give food, or rub a little corn syrup or honey on the gums, and call your vet. If your dog is seizing or unconscious, don’t put anything in its mouth. Go to an emergency vet.
Monitoring
- Glucose curves: a series of blood sugar checks over a day, at the clinic or at home.
- Continuous glucose monitors: small sensors on the skin that many vets now use.
- Daily observations: track water intake, urination, appetite, weight, and energy.
Complications
- Cataracts: most diabetic dogs develop them, often within the first year. Cataract surgery can restore vision in suitable dogs.
- Urinary infections.
- DKA, especially when diabetes isn’t well controlled.
What to avoid
- Changing insulin doses without your vet.
- Treats outside the plan, especially sugary or fatty foods.
- Herbal diabetes supplements in place of insulin.
Frequently asked questions
Can diabetes in dogs be reversed?
Rarely. Most dogs need lifelong insulin. Some females become insulin-free after spaying if diabetes was triggered by heat hormones.
How long do diabetic dogs live?
Many dogs that survive the first few months after diagnosis live for years with good control.
Can my dog take pills instead of insulin?
Oral diabetes medications used in people aren’t effective for most dogs.
Sources
- Behrend E, et al. 2018 AAHA Diabetes Management Guidelines for Dogs and Cats. J Am Anim Hosp Assoc. 2018
- Beam S, et al. A retrospective-cohort study on the development of cataracts in dogs with diabetes mellitus: 200 cases. Vet Ophthalmol. 1999
- Merck Veterinary Manual: Diabetes mellitus in dogs and cats
- Fracassi F. Canine diabetes mellitus. In: Ettinger SJ, et al. Textbook of Veterinary Internal Medicine. Elsevier
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.