Diabetes Mellitus…a not so sweet illness…

Left untreated, this disease can have serious effects and will ultimately result in the death of your pet. Thankfully, the majority of diabetic pets can now be treated and may live normal, happy lives, providing that owners are prepared and able to invest both time and finances into their care.

Diabetes Mellitus (sugar diabetes) is a relatively common disease seen in older people, and is being recognised more frequently in older pets.


Diabetes Mellitus (DM) is caused by a lack of, or resistance to, the hormone insulin, which keeps blood sugar (glucose) at an optimum level. When there is a lack of insulin, sugar from food builds up in the blood and eventually starts to appear in the urine.


Animals with diabetes will have high blood glucose levels along with glucose in their urine (glucosuria). They will be more thirsty than usual (polydipsia) and subsequently have increased urination (polyuria). These animals also often lose weight despite having a good appetite.

Other illnesses may develop if DM is left untreated, such as liver and kidney issues, eye disorders and diabetic neuropathy (nerve damage resulting in weakness, especially of the back legs). Prolonged untreated DM can result in a complication called Diabetic Ketoacidosis, where your pet can become extremely ill with depression, vomiting, diarrhoea, anorexia and collapse. This is an emergency situation, and without veterinary intervention, coma and death is likely.


Your pet’s clinical signs may suggest DM as a differential diagnosis, however, there are other conditions that can produce similar symptoms so further investigations are necessary to confirm a diagnosis. URINE analysis will show the presence of GLUCOSE and possibly KETONES (ketones are used as an alternative source of energy during DM). BLOOD TESTS will show a high concentration of GLUCOSE, and FRUCTOSAMINE concentrations may also be analysed to give an average blood glucose concentration over the preceding weeks.


Most diabetic cats and dogs will require treatment with injections of insulin, however the type of insulin used and adjunctive therapies can vary between the two species.


Most diabetic cats will require twice daily injections of an intermediate or long-acting insulin preparation, to control their blood sugar levels. Dietary considerations are also a major factor in the management of DM in cats.

Firstly, if your cat is overweight (diabetic cats are frequently obese), then it is very important to normalise their bodyweight to “ideal”. In some instances, this in itself can result in diabetic remission, due to the fact that obesity interferes with the action of insulin.

Cats with DM also benefit greatly from a diet that is LOW IN CARBOHYDRATES and HIGH IN PROTEINS, so feeding a prescription diabetic diet will help ensure a proper balance of all the essential nutrients your cat needs.


Diabetic dogs require regular insulin injections to control their blood sugar levels, usually given once or twice daily. Unlike cats, diabetic remission is not seen in dogs, and so insulin injections will be required for the rest of your dog’s life.

Your dog’s diet must also be very strictly managed in order to control the diabetes. This means feeding only the prescribed diet without any titbits or treats, with feeding times and exercise all carefully coordinated around the insulin injections, in order to obtain successful management of the disease. Prescription diabetic diets are also available specially formulated for dogs, and unlike the feline diets, they tend to contain a higher level of slow-releasing carbohydrate to reduce surges in blood glucose levels following feeding. This can also cause a satiety effect, helping your dog to feel fuller for longer, which can be useful in cases where weight loss is required.


Diabetes Mellitus can be a complex and sometimes frustrating disease to treat and control for both cats and dogs, and sadly not every pet responds well to treatment. Many pets however, can continue to have an excellent quality of life, and live very happily with their diabetes if they are well managed, whilst being very rewarding to treat for both their dedicated owners and the veterinary team.