Diabetes mellitus (DM) is an endocrine disorder that occurs in both dogs and cats.  It is caused by the relative or absolute deficiency of the hormone insulin, which is produced by the beta cells of the pancreas.  Insulin stimulates the transport of glucose and other nutrients across cell membranes for cellular use and is involved in a number of anabolic processes within the body.  A lack of insulin activity leads to elevated blood glucose levels (hyperglycemia) and an inability of tissues to receive the glucose that they need (glucoprivation).  Primary clinical signs include polyuria, polydipsia, polyphagia, and, in some cases, weight loss.  Diagnosis is usually made using the initial signs of the disorder, which include the presence of a persistent hyperglycemia and a persistent or concurrent glucosuria.