Diabetes mellitus

Fat Cat sitting on gravelDiabetes mellitus, usually shortened to just ‘Diabetes’, can affect any cat but is most commonly diagnosed in middle-age or old-age.  Male cats are most commonly affected and it is more common in cats who are, or have previously been, overweight.  Burmese cats have been shown to be especially prone to diabetes.

Diabetes is caused by a reduction in the production or sensitivity of the body to insulin, a hormone produced by the pancreas which regulates sugar levels in the body.  When insulin is released, sugar in the blood stream will move into the body’s cells, providing them with energy.  In diabetes, this doesn’t happen, so the blood has a high level of glucose in it, but the cells are starved of glucose, so they cannot produce energy effectively.

In humans, there are two recognised forms of diabetes:

  • Type 1 diabetes is an autoimmune disease which causes the destruction of the insulin-producing cells in the pancreas and is usually diagnosed in children and young adults
  • Type 2 diabetes is caused by exhaustion of the insulin-producing cells and insulin resistance in the body’s cells.  This form is most commonly diagnosed in older, overweight adults.

Diabetes in cats is very similar to Type 2 diabetes.  However, many humans with type 2 diabetes can be controlled with diet and tablets whereas most cats will need insulin injections, at least initially.

Some other diseases and medications can make a cat more prone to developing diabetes:

  • Hyperadrenocorticism (Cushing’s disease) leads to an overproduction of steroid hormones from the adrenal glands
  • Acromegaly is caused by an excessive production of growth hormone from the pituitary gland
  • Treatment with steroids (e.g. for skin irritation, inflammatory bowel disease)
  • Treatment with progesterone-like drugs




The common signs of diabetes are:

  • excessive drinking and urinating
  • weight loss (usually in an overweight cat)
  • increased appetite

Other signs you might notice include:

  • weakness, particularly of the back legs
  • poor coat condition
  • straining to urinate or blood in urine (the sugar in the urine makes urinary infections more likely)
  • vomiting, off food, collapse – these are signs of potentially-fatal diabetic ketoacidosis and need URGENT treatment by your vet

Blood samplesTo diagnose diabetes, your vet will want to do a blood sample and a urine test.  The diagnosis is based on elevated glucose in the blood stream and glucose in the urine.  The fructosamine level will be tested to ensure that the elevation in blood glucose is not just a one-off – this value gives an indication of the blood glucose over the previous 2-3 weeks.



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