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Like many diseases common to people and animals, diabetes mellitus is a frequently diagnosed condition in pets, especially middle aged to older cats and dogs. In cats, it’s more common in males.

Diabetes mellitus results from failure of the beta cells in the pancreas to produce enough insulin. The pancreas is a small but critical organ attached to the upper small intestine near the stomach and liver. It has two functions – producing enzymes to aid in digestion and producing insulin to help the body utilise sugars, fats and proteins.

Pets develop the same types of diabetes as we do: Type 1 (genetic, this is rarely diagnosed in dogs and cats) and Type 2 (acquired, see predisposing conditions below. Certain breeds of cats, including Burmese, are thought to be more susceptible to Type 2).

What initiates diabetes mellitus?

Again, as in people, there are a number of predisposing conditions leading to Type 2 diabetes. Overweight cats are more prone to diabetes. Pets that have had pancreatitis – an inflammation of the pancreas more common in dogs – are also at higher risk of developing the disease. Certain drugs, including cortisone-type drugs and some hormones (especially those used for controlling oestrus) can initiate diabetes, especially if used for long periods.

Symptoms and clinical signs

When the body lacks insulin, sugar accumulates in the blood stream and excess spills into the urine. These high levels of sugar in the urine causes two key signs: polyuria and polydipsia. That is, the cat will begin to pass large amounts of urine and drink lots of water. The pet will be constantly hungry but at the same time, will lose weight as the nutrients in its diet are not being processed efficiently.

Other possible signs in cats include fat accumulation in the liver and infections in various organs. Cats rarely develop cataracts as dogs do, but they can develop an impaired jumping ability and abnormal stance and gait.

Cats with Type 1 diabetes will often show the above clinical signs (excess urination and drinking, and weight loss despite a good appetite) without being particularly unwell. Cats with the more common Type 2 diabetes become seriously ill, and are often presented to CVH vomiting, weak and depressed.


Clinical signs of excess drinking and urination, backed up by the detection of high levels of sugar in the urine and blood, confirm a diagnosis of diabetes mellitus. A sweet odour may be noted on the breath if the animal is ketotic. A blood screen of other organs is essential to check for abnormalities in the liver, kidney and pancreas and diabetic patients with ketoacidosis may have an elevation in their blood stream of waste products that are normally removed by the kidneys.

It’s also essential that middle-aged or older cats (over 7 years) presented with weight loss and increased appetite are tested for hyperthyroidism – in cats, diabetes and hyperthyroidism cause similar clinical signs and can occur at the same time.


Pets with diabetes require individual, carefully monitored treatment regimes. This usually includes 12-hourly insulin injections and always, a tailored, appropriate diet.

Undertaking treatment is a huge commitment for the pet owner. CVH vets give our clients as much information as possible – it’s essential the pet’s owner understands the requirements for successful treatment of diabetes before we begin the task of stabilising their cat for long term treatment.

The aim of treatment is to replace enough of the body’s insulin so clinical signs are controlled, but hypoglycaemic episodes (low blood sugar from too much insulin) are avoided. It’s been said that the treatment of diabetes is a combination of art and science – each animal needs an individualised treatment regime, frequent reassessment and treatment modified based on response.

The insulin injections are given under the skin with very fine needles. Insulin dosing syringes are easy to use and allow accurate measuring of the small insulin doses required for cats.

One of the trickiest things is to master is the collecting and testing of urine from cats. Our vets can help with some easy, practical ways to ensure litter-free urine is collected for testing.

Diet modification

Managing the diet of diabetic cats is critical and to make life easier, we stock both canned and dried prescription diets for diabetic pets. For overweight diabetic cats, it’s essential to get the pet’s body weight back to normal – we can assist with helping to devise a weight loss diet that’s also safe for cats with diabetes. Alongside achieving weight loss is the need to feed a high protein/low carbohydrate diet. Protein provides a good energy source and prevents the loss of lean muscle mass, while carbohydrates can contribute to hyperglycaemia – feeding a diet low in carbohydrates is essential. The frequency of feeds will also be important and this can include a regime of more frequent small meals given at specific intervals. 

After the initial diagnosis

Once a diabetic pet is stabilised, successful ongoing treatment requires excellent teamwork and regular communication between the client and our vets. Clients need to become even more observant of their cat’s behaviour and health, learn how to monitor urine for sugar with dipsticks, and report any concerns promptly. It’s important to keep a daily record of injections and dose, water and food intake and appetite, the presence or absence of glucose in the urine, and to weigh your cat regularly.

At CVH, we are well-experienced in the diagnosis and treatment of diabetes, but it is not an easy disease to manage and a successful outcome requires much dedication and patience from the cat’s owner – and, an amenable cat. But it’s also remarkable how many feline companions accept and become accustomed to their twice-daily injections, going on to live happily for years after their diagnosis of diabetes.