Diabetes mellitus is a hormone deficiency that leaves a dog unable to regulate his blood glucose (sugar) properly. This can result in clinical symptoms that include increased drinking, increased urination, weight loss, cataracts, and other metabolic abnormalities that can result in severe illness and death.
The primary problem is a lack of insulin. Insulin is a hormone produced by the pancreas. Normally, the pancreas releases insulin into the bloodstream to control the use of glucose, the preferred form of fuel used by the cells of the body. Without insulin, the cells cannot access to glucose in the bloodstream, and that glucose, which comes from digested carbohydrates or released from storage within the body, builds up to abnormally high levels that can damage the dog’s other organs.