Diabetes mellitus is one of the most common hormonal diseases diagnosed in our dogs and cats. Diabetes is a condition in which the pancreas is unable to produce insulin in sufficient amounts. Without insulin, the body cannot utilize its main energy source, which is glucose (sugar). Therefore the body must use the alternative energy sources fat and protein. As the body breaks these sources down, the animal loses weight which can be significant. Even though the body cannot utilize blood sugar, it remains very high in the blood which leads to excessive drinking and urination. (Remember the more sweet drinks we drink, the thirstier we become.)
Diagnostically, diabetes can easily be diagnosed with very high blood sugar levels. Secondary tests such as a urinalysis are often performed to rule out concurrent urinary tract infections and ketoacidosis which is a more severe form of diabetes.
Dogs and, to a lessor extent, cats will often develop cataracts as a secondary condition. Long term conditions such as neuropathies, liver and kidney issues, etc that are more common in humans do not typically affect our pets simply due to the length of time it takes to create those problems.
Although we cannot characterize dog and cat diabetes as we do with humans, it is similar. Dogs are more likely to exhibit a Type one, or insulin dependent diabetes much like children. The pancreas of dogs will often either completely stop production of insulin, or it will dramatically decrease its production. Cats are more similar to adult onset diabetes, or Type two (non-insulin dependent) diabetes. Therefore, dogs almost always require insulin injections to control blood sugar. Cats often times require insulin injections but can otherwise be controlled with diets high in fiber and low in simple sugars or carbohydrates.
The goal of diabetes therapy is to decrease the clinical signs of excessive drinking, excessive urination, excessive appetite, and cataract formation. It is ideal to get the blood sugar into a more normal range, but that is not the primary goal. Unlike people who will check their blood sugar multiple times a day, that is impractical in our pets. We will spot check blood sugar weekly until we feel a good regulation has occurred. Therapy is often required for life in dogs. Dietary management may be all that is required for cats.