Diabetes mellitus, or sugar diabetes, is found more common in certain breeds of dogs. German Shepherds, Miniature Schnauzers, Golden Retrievers, Poodles and Keeshonden have the highest incidences, however all breeds can be found with this disease. It is more common in female dogs on a three to one rate, and the onset is generally seen in 6 to 9 year old dogs.

The pancreas produces insulin and diabetes is a result of an inadequate production by the islet cells. It is thought that there could be a genetic predisposition for the above mentioned breeds. Islet cell damage can occur in cases of pancreatitis. The energy that is produced for metabolism is enabled by the glucose that passes into the cells, which is supported by consistent insulin levels. A deficiency in insulin results in hyperglycemia (high blood sugar) and glycosuria (high urine sugar). If large volumes of urine are being produced by the animal and glucose is found in the urine then the diagnosis is diabetes. This may result in dehydration and the animals urge to drink large amounts of water.

Initially, dogs that do not metabolize enough sugar have an increase in appetite and a desire to consume more food, however later, with the effects of malnourishment, the appetite drops. The early signs of diabetes include drinking a lot of water, followed by frequent urination, a larger appetite with unexplained loss of weight.

Diabetes will be detected in the laboratory when high levels of glucose are found in both the blood and the urine. .