Feline diabetes mellitus is one of the most common metabolic diseases in domestic cats, with an estimated prevalence of 1 case per 100-500 cats. Like human type 2 diabetes, the most common form in cats involves insulin resistance and relative insufficiency of pancreatic beta cells. The good news is that, with correct diagnosis and rigorous management, many diabetic cats achieve remission and no longer need insulin.
Risk Factors: Which Cats Are Most Likely?
Several factors increase the risk of diabetes mellitus in cats:
- Obesity: the most important risk factor. Visceral fat generates chronic inflammation and insulin resistance. Obese cats have a 4 times higher risk of developing diabetes than cats at ideal weight.
- Male sex: neutered males have a greater predisposition than females.
- Age: more common in cats over 8-10 years old.
- Breeds: Burmese and Maine Coon have greater genetic susceptibility.
- Prolonged glucocorticoid treatment: corticosteroids induce insulin resistance and can trigger diabetes in predisposed cats.
- High-carbohydrate diet: chronic consumption of dry foods with high starch content can overload pancreatic beta cells.
Symptoms: When to Suspect Diabetes
The four cardinal symptoms of feline diabetes are:
- Polyuria (urinating a lot): the litter box fills up more quickly and the cat may start having accidents outside it.
- Polydipsia (drinking a lot): the water bowl needs refilling more frequently.
- Polyphagia (eating a lot): the cat eats more than usual but loses weight.
- Progressive weight loss despite increased appetite.
In more advanced stages, plantigrade stance may appear (the cat rests its hocks on the ground when walking, due to peripheral diabetic neuropathy), along with lethargy, vomiting and anorexia (diabetic ketoacidosis).
Diagnosis: Beyond Blood Glucose
An elevated blood glucose alone is not enough to diagnose diabetes in cats: stress itself can raise blood glucose up to 400 mg/dL in a non-diabetic cat (stress hyperglycemia). Diagnosis requires:
- Elevated fasting blood glucose (>270 mg/dL) on more than one measurement.
- Persistent glucosuria (glucose in urine).
- Elevated serum fructosamine: reflects average blood glucose of the previous 2-3 weeks and is not affected by acute stress. It is the most reliable marker for diagnosis.
Treatment: Insulin, Diet and the Possibility of Remission
Treatment of feline diabetes has three fundamental pillars:
Insulin: glargine (Lantus) or detemir (Levemir) are the long-acting insulins of choice in cats for their species-appropriate pharmacokinetics. They are administered every 12 hours by subcutaneous injection, generally in the dorsal skin fold. The dose is adjusted based on home blood glucose monitoring (glucometer or flash monitoring).
Low-carbohydrate, high-protein diet: this is the most impactful change in modern feline diabetes management. Diets with less than 10% carbohydrates in dry matter (generally wet foods) drastically reduce postprandial insulin demand and facilitate remission. Prescription diets such as Hill's m/d or Royal Canin Diabetic are formulated for this purpose.
Weight control: weight loss in obese diabetic cats reduces insulin resistance and increases the chances of remission.
Diabetic Remission: An Achievable Goal
Remission is defined as normalization of blood glucose without the need for insulin for at least 4 weeks. In cats treated with long-acting insulin and a low-carbohydrate diet from diagnosis, remission rates can reach 50-80% in the first 6 months. The key is to act quickly: the longer beta cells have been damaged by glucotoxicity, the lower the chance of functional recovery.
Cats in remission should continue to be monitored, as diabetes can recur, especially if they regain weight or receive glucocorticoids.
