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Feline Diabetes Mellitus

Animals are very similar to humans in a number of ways, including some of the medical conditions we see. Diabetes is the most common hormonal disorder seen in cats. As in humans, diabetes in cats can appear as two different forms: Type I or Type II.

In diabetes mellitus there is either

1: a lack of insulin (Type I - Insulin dependent) or

2: a lack of response to insulin or reduced insulin production (Type II - Insulin non-dependent).

Insulin is a hormone secreted by small groups of cells in the pancreas (Beta cells) and is needed by all cells to allow glucose to enter them to be used as an energy source. When glucose can’t enter the cells the blood levels rise and the cells have to use fat and protein (muscle) as an energy source. This sequence of events leads to a myriad of problems to occur.

Clinical Signs

• Excess drinking & urinating because when the high levels of glucose are excreted in the urine they take water with them

• Weight loss because when the cells can’t use glucose for energy so they start to metabolise the body’s fat stores

• Excess eating because glucose can’t enter the cells in the brain which regulate appetite

• A syndrome unique to cats where some nerves of the hind legs degenerate and a "dropped hock" appearance occurs. The back legs may also appear weak

 Cause of Diabetes

Type I diabetes is caused by the body’s immune system destroying the small groups of cells (beta cells) in the pancreas which make insulin. Eventually there is almost total loss of these beta cells and the patient requires insulin injections for survival.

Type II diabetes is poorly understood as compared to type I. There are different processes occurring in the insulin producing cells and the cells of the body appear to become resistant to the effects of insulin. Type II diabetes is similar to mature onset diabetes in people and therefore affects the same groups of patients ie:

Age - in Australia two thirds of diabetic cats are over 10 years old

Obesity - overweight cats are many times more likely to develop diabetes

Sex - more male cats than females get diabetes ( although in humans worldwide there is no gender predisposition)

Inactivity - although no studies have been done one may assume that the average domesticated cat being less active than a feral cat, is more likely to develop diabetes. This is definitely the case in humans where physical inactivity increases the risk

Treatment

Generally in human medicine Type I diabetics require regular insulin injections whereas type II diabetics are treated with other drugs.

Many cats appear to have type II diabetes ( also know as non-insulin dependent). There is also a phenomenon in cats called Glucose Toxicity which helps to explain why Type II diabetic cats may respond to insulin injections.

Continual high levels of glucose in the blood will suppress the production of insulin by the beta cells of the pancreas, eventually leading to degeneration of these beta cells. Therefore a cat that starts off as a Type II diabetic ends up clinically similar to a Type I diabetic and needs to be treated accordingly (ie insulin). Humans don’t seem to be affected as much by Glucose Toxicity therefore Type II diabetic humans can usually avoid the use of insulin and just use drugs to increase there own insulin production.

Type I diabetics: usually require insulin injections

Type II diabetics: in humans drugs are used to increase the body’s insulin production. As explained before, although most cats have Type II diabetes, they tend to still require insulin injections due to problems from Glucose Toxicity.

Initially we will take blood to look for any underlying causes which could cause diabetes as a secondary condition. There are several regimes of diabetic management that can be used. Your veterinarian will advise on the best regime and diet to follow to manage your cat's case.

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