Diabetes mellitus is a complicated condition caused by either an absolute or relative deficiency of insulin. Insulin is a hormone normally produced by the pancreas that is secreted into the bloodstream after eating. It’s main role is to enable cells to take up glucose (sugar) which is needed as an energy source. Insulin also stimulates the uptake of various other substances, including amino acids (building blocks for protein) and fatty acids. In diabetic cats, a deficiency of insulin results in impaired uptake of glucose by tissue cells, which causes hyperglycaemia (high blood glucose levels) and glycosuria (glucose in the urine). As the cells are starved of glucose, they switch to using fat and protein as an energy source, resulting in weight loss and the accumulation of toxic waste products which can precipitate a diabetic crisis.
The majority of diabetic cats are classified as type 2 (or adult onset diabetes), which is characterised by a combination of insulin resistance and inadequate insulin secretion. Insulin resistance describes the situation whereby cells of the body fail to respond to insulin as effectively as they should. Insulin resistance can be caused by a number of conditions, including obesity, systemic disease and certain drugs. Sedentary lifestyle and high carbohydrate diets are also significant risk factors. Most cats are older than 6 years at the time of diagnosis, with a peak incidence between 10 and 13 years of age. Burmese cats are over-represented.
Diabetes mellitus results in high blood glucose and glucose in the urine. The presence of glucose in the urine results in an increased volume of urine (polyuria). To compensate for this, diabetic cats will have an increased thirst (polydipsia). Weight loss despite an increased appetite may also be seen. In a small number of diabetic cats, a peripheral neuropathy may develop, in which the nerves supplying the hindlimbs are affected, resulting in a plantigrade stance (dropped hocks). Most diabetic cats will remain well in themselves, but ketoacidosis is a potential complication. In this situation, the cat may become extremely depressed, with signs such as inappetence, vomiting, diarrhoea, dehydration, collapse. Diabetic ketoacidosis is a life threatening complication.
Blood and urine tests are required to confirm a diagnosis of diabetes mellitus and to assess for underlying causes of the diabetes and potential secondary complications, such as a urinary tract infection. In some cases, a fructosamine level may need to be performed. Fructosamine is a measure of glycated protein, which indicates that blood glucose levels have been elevated over the past 2-3 weeks, allowing diabetes to be distinguished from stress associated high blood glucose.
Treatment of cats with uncomplicated diabetes mellitus involves dietary management, use of injectable insulin, and regular monitoring of blood and urine glucose levels. With appropriate treatment, between 60-90% of diabetic cats go into remission within 3-4 months of diagnosis and no longer require insulin injections.
1. Dietary management - New prescription “diabetic” diets have been designed that are high in protein and in low carbohydrate, which results in decreased insulin requirements (eg. Royal Canin Diabetic, Hill’s M/D). Overweight cats are fed special weight reducing diets, aiming to reduce weight gradually over 2-4 months (eg. Royal Canin Obesity).
2. Insulin therapy - Insulin is given by an injection under the skin. Most cats require twice daily injections and it is important that the insulin is given at the same time every day as directed by your veterinarian. Special insulin syringes with very fine needles are used so that the cat will hardly feel the injection. Insulin should be kept in the fridge. Before withdrawing insulin for administration, the insulin vial should be gently rocked back and forth so that an even suspension is obtained. There is a high degree of individual variability in insulin dosing, so most cats will need to be hospitalised for a short period when being commenced on insulin therapy.
3. Monitoring of blood and urine glucose levels - Initially most cats will need to come into the clinic for serial blood glucose monitoring. The main aims of blood glucose monitoring is to establish the peak action of insulin, duration of insulin and an appropriate insulin dose. Several other parameters are also monitored, including body weight, water intake and urine glucose levels. Initial stabilisation can take a few days to a couple of weeks. After a few weeks, at home monitoring ca be performed. This involves monitoring water intake, appetite and body weight, as well as measuring blood glucose and urine glucose levels (see home monitoring handout).
Checking your cats blood glucose level:
To enable you to monitor your cat’s blood glucose levels as home, you will need to purchase a human glucometer (either from us or a pharmacy). We recommend Accu-check (HUMAN) or the Alphatrak (CAT SPECIFIC) , as this requires the smallest volume of blood, however another equivalent brand would also be suitable. Blood may be sampled from the marginal ear veins or the foot pads.
4. Continuous glucose monitoring devices - skin implant devices are commonly used in cats (human devices) for initial management and stablisation of cats with diabetes. They give an approximation of contiuous 24hr record of your cats glucose levels. The average device lasts about 8-9 days, many cats remove them or they simply stop working (human specific) - some clients learn how to place these on their own cats at home - any easy skill to master
5. New ORAL diabetes & weight loss drugs have also been regustered in cats. Initial studies show extremely prommising results for management of feline diabetes. This may
Hypoglycaemia
The most life-threatening complication that can develop at home is hypoglycaemia, or low blood glucose. This can occur if too much insulin is given. The main signs of hypoglycaemia are weakness, lethargy, disorientation, drunken gait or strange behaviour. Rapid recognition of these clinical signs is needed to prevent progression to severe signs, such as collapse, coma or even death. If clinical signs are observed, the cat should be encouraged to eat glucose syrup or honey. This should be applied directly to the gums. Owners should then contact the clinic for advice. Severely hypoglycaemic cats may need to be admitted into hospital for intravenous glucose administration and stabilisation.
