Signs of Diabetes in Cats: Symptoms and When to Test

Feline diabetes announces itself through the litter box before anything else. The cat drinks more because its body is shedding glucose into the urine, and it urinates more to keep up. Most owners notice the second part first — a litter box that needs changing more often, or clumps that are noticeably bigger.

The Four Classic Signs

• Drinking more (polydipsia) — refilling the bowl more often, or a cat that starts drinking from taps and glasses when it never did.
• Urinating more (polyuria) — usually spotted as a heavier litter box rather than as more frequent trips.
• Weight loss — often gradual, and frequently the sign that finally prompts the vet visit.
• Appetite change — classically increased hunger, but see below, because this one misleads people.

The Sign That Misleads Owners

Diabetes is widely described as making cats ravenous, and plenty of diabetic cats do eat more. But the Merck Veterinary Manual notes that up to 50% of cats with diabetes mellitus have a decreased appetite. That single fact undoes the most common piece of owner reasoning about this disease: my cat is not eating more, so it cannot be diabetes.

Weight loss is the more dependable signal. A cat that is losing weight while eating normally is worth investigating, and a cat losing weight while eating less is worth investigating urgently — that combination can also point to hyperthyroidism, kidney disease, or several other conditions that look similar from the outside.

The Sign Specific to Cats: Walking Flat on the Hocks

Diabetic neuropathy occurs mainly in cats rather than dogs, and it produces a posture that is unmistakable once you know it. The cat's hocks — the joints partway up the back legs — drop toward the floor, so it walks flat-footed on its rear legs instead of up on its toes. This is called a plantigrade stance.

It matters because it is not an early sign. A cat walking this way has usually had untreated diabetes for a while, and the neuropathy is the nerve damage that follows. It is a reason to call the vet this week rather than mention it at the next routine visit.

Which Cats Are Most at Risk

Diabetes shows up in middle-aged and older cats, and prevalence is higher in cats weighing more than 4 kg. Several breeds are predisposed: the Tonkinese, Norwegian Forest Cat, Burmese, Russian Blue and Abyssinian.

One useful difference from dogs: diabetic dogs commonly develop cataracts, and diabetic cats do not. Cloudy eyes in a cat point somewhere else.

Why One High Reading Is Not a Diagnosis

Cats develop stress-induced hyperglycaemia easily, and a car journey plus a waiting room is enough to raise blood glucose on its own. That is why a single high number at the vet does not settle the question. Diagnosis needs persistent hyperglycaemia together with glucose in the urine.

Where the picture is ambiguous, a fructosamine test separates the two. It reflects average glucose over the preceding weeks rather than the moment of the blood draw, so it stays normal in a stressed cat and rises in a genuinely diabetic one. For what the numbers themselves mean, including normal ranges and what different glucose levels indicate, see the cat blood sugar guide.

Frequently Asked Questions

Sources

• Merck Veterinary Manual — Diabetes Mellitus in Dogs and Cats