Diabetes is the inability to produce or respond to insulin the hormone in our body that is responsible for moving glucose (the body’s sugar) into the body’s cells. This leads to an increased level of glucose in the bloodstream as the cells are unable to take it up.
Some of the signs of diabetes include urinating more as glucose is lost in the urine which drags water with so they have to drink more. Animals tend to be hungry as their cells are unable to use the glucose in their blood, but they lose weight as their body uses up fat stores and muscles for energy. With poorly controlled diabetes we can see nerve damage, particularly to the nerves of the back legs which can lead to a plantigrade stance - which is where the animal walks on its hocks (ankles). We can also see sudden blindness with diabetic cataracts.
Diagnosis of diabetes is made from blood and urine tests. In cats we have to be a bit more careful with the interpretation of these tests as stress can cause a cat’s blood glucose levels to increase. Even a ride in the car to the vet can cause its blood glucose to rise, not to mention the taking of blood. This means that with cats we often need to test a fructosamine level, which is a blood test that shows us what the average blood glucose is over the last few weeks as this test will differentiate between the level of blood glucose going up from stress or disease. Dogs don’t tend to get high levels with stress, so we don’t often need to do a fructosamine level initially but can use it for monitoring.
Interestingly, most dogs are the equivalent of type 1 diabetics where they fail to produce enough insulin, the body’s hormone that is responsible for blood sugar regulation. Whereas most cats tend to be type 2 diabetics - where they become resistant to the effect of insulin. However, over time this leads to damage to the pancreas, the organ that produces insulin which means it will no longer produce insulin.
This means that animals require insulin therapy to control their diabetes. In cats, it has been shown that if you treat with insulin and a low carbohydrate, high protein diet and start that treatment in the first 6 months of the cat having diabetes, 80% of cats will go into remission and no longer be reliant on insulin. However they do need to stay on the low carbohydrate, high-protein food and most do become insulin-requiring diabetics again sometime in the future.
While cats do better with low carbohydrate, high protein diets, dogs do better with high fibre diets as with dogs this tends to slow the absorption of glucose from the gut.
With insulin therapy, we need to be careful that the blood glucose levels don’t go too low as this can lead to weakness, collapse, seizures and death. Monitoring can be done by taking a series of blood samples over the day to see how the levels change throughout the day, or by way of a sensor that attaches to the animal for up to 2 weeks. The sensor is scanned using a reader or an app on your phone to get a reading of the glucose levels.
Occasionally an animal can present in diabetic ketoacidosis (diabetic shock) where they become very ill with vomiting, anorexia, lethargy and severe dehydration. They often have severe electrolyte derangements as well as their blood becoming acidic. This can occur to a non-diagnosed diabetic or to a diabetic on treatment, normally the result of an infection (such as a urinary tract infection) or inflammation, such as an episode of pancreatitis. These animals often require a few days of hospitalisation with intensive fluid therapy and electrolyte correction as well as careful monitoring and control of their blood glucose level.