Diabetes Mellitus in Cats

What is diabetes mellitus?

Diabetes mellitus refers to a medical condition where there is an excessive quantity of sugar (glucose) in the blood. This is caused by a relative or absolute deficiency of the hormone insulin, which is secreted by the pancreas.

The clinical signs seen in diabetes are largely a consequence of the raised concentrations of glucose in the blood, and the inability of the body to use glucose as an energy source (due to the deficiency of insulin).

Diabetes mellitus is a relatively common disease in cats, seen most frequently in middle to old-age cats.

What clinical signs do you see in diabetes mellitus?

The most common clinical signs seen in diabetic patients are an increase in the volume of urine that is produced and, to compensate for this, an increase in the amount of water that is drunk. Weight loss is also a common feature, and an increase in appetite may be noticed in some cats. Recognition of these signs is variable though, particularly because of the life-style of some cats. If a cat spends a lot of time outdoors for example, it may drink from ponds or pools of water outside rather than appearing to drink excessively from what is provided indoors.

"The most common clinical signs seen in diabetic patients are an increase in the volume of urine that is produced and, to compensate for this, an increase in the amount of water that is drunk."

How is diabetes mellitus diagnosed?

The diagnosis of diabetes mellitus is made by finding appropriate clinical signs, together with a persistently elevated blood glucose concentration and the presence of glucose in the urine. However, a diagnosis of diabetes cannot usually be made on a single blood and urine sample as other conditions, and in particular stress, may also cause a transient rise in glucose levels. Confirmation of diabetes may therefore require more than one blood sample collected over a period of time (perhaps several days), and measurement of another substance in the blood (Fructosamine) that gives an indication of average blood glucose levels over the previous 2-3 weeks.

How is diabetes mellitus treated?

Diabetes mellitus is a treatable condition. Although long-term treatment does require commitment, it can be very rewarding to successfully manage this condition.

Initial steps in treating a diabetic cat may involve removal of any predisposing causes for the diabetes. For example, the administration of some drugs predisposes cats to develop diabetes, and withdrawal of these drugs may lead to resolution of the condition. Also obese cats are more prone to develop diabetes and again, reduction in bodyweight can lead to resolution of the signs in some of these individuals.

If there are no predisposing causes, or if correction of the predisposing causes does not lead to resolution of the diabetes, specific treatment is required. Although a very small proportion of cats will respond to a form of tablet (‘oral hypoglycaemic’) designed to increase the amount of insulin produced by the pancreas and increase its effectiveness, the majority of cats will require insulin supplementation in the form of injections to control the diabetes.

During the initial stages of treatment, it is common for a cat to be hospitalised at a veterinary surgery so that appropriate monitoring can be carried out while a suitable dosage and preparation of insulin is being determined. Once a cat has been stabilised (which usually takes a few days to a week or so, but occasionally can take a lot longer), treatment can be continued at home. This involves usually twice daily injections of a small dose of insulin. Very small needles are available for this which cause minimal pain to the cat, and within a short period of time the procedure becomes very routine. Normally the insulin will be administered first thing in the morning just after feeding the cat and again in the evening. Your veterinarian will advise you further on the type of food to use and the timing of feeding, depending on your individual cat’s requirements. There is a lot of individual variation in the response to insulin and you must follow closely any advice given to you by your veterinarian.

Do treated cats need to be monitored?

Yes, it is important to monitor treatment to make sure it is working properly, and to determine if any adjustments are necessary to the dose of insulin given.

Monitoring can be done in part through collection of occasional blood samples by your veterinarian, but it is particularly valuable to keep accurate records of the following information:

Daily records:

• Time of insulin injection
• Amount of insulin injected
• Amount of food fed and eaten (and time)
• Amount of water drunk

Weekly record:

• Weight of the cat

Sometimes your veterinarian may ask you to collect a urine sample at home. To collect urine, it is easiest to replace the normal cat litter with a non-absorbent litter that will be supplied by your veterinarian, or acquired at a pet shop. The urine will not be absorbed and therefore can be sucked up with a syringe and placed in a sterile container. The urine collected can either be tested by your veterinarian, or they may supply you with a kit to test it yourself. It is important that you never change the dose of insulin without first discussing it with your veterinarian. Changes in the insulin dose are usually based on trends in urine and blood glucose concentrations as well as further blood test results and the clinical signs that your cat is showing.

What happens if my cat receives too much insulin?

If a cat receives too much insulin (or if receives the normal amount but doesn’t eat for some reason), it is possible for the blood sugar level to drop dangerously low. For this reason it is important to be very careful in ensuring the cat receives the correct dose of insulin and not to continue insulin treatment if your cat stops eating for any reason.

The typical signs displayed by a cat with a very low blood sugar level are severe weakness and lethargy, shaking, unsteadiness and even convulsions. If a diabetic cat shows any of these signs it is important to seek urgent veterinary attention. If the more severe signs are displayed (unsteadiness during walking, and/or convulsions) a tablespoon of a saturated glucose or sugar solution should be given by mouth immediately. As this is an emergency, it is useful to have a small amount of a glucose solution stored in a refrigerator for any cat receiving insulin.

Will my cat require insulin for the rest of their life?

Recent advancements in feline diabetes have led to the understanding that some cats can go into “remission” and no longer be insulin dependent.