Sarah, a 14 year old female spayed domestic shorthair cat, presented to the Cornell University Hospital for Animals with a chief complaint of polyuria, polydipsia, polyphagia and weight loss of several weeks duration with a recent onset of weakness, lethargy and anorexia. Clinical findings on physical examination and diagnostic evaluation included thin body condition, dehydration, hyperglycemia, glucosuria, ketonuria, and electrolyte and acid-base abnormalities. A diagnosis of diabetes mellitus with ketoacidosis was made and insulin and fluid therapy were instituted. Sarah was initially sent home on Humulin-N NPH insulin twice daily. A recheck 3 weeks later revealed persistent hyperglycemia and elevated fructosamine level. In addition, she remained symptomatic for her diabetes mellitus. Over the next several months, serial blood glucose curves and fructosamine levels were performed to help evaluate her glycemic control. A discussion of the dietary and medical management strategies of diabetes mellitus, as applied in Sarah's case will be reviewed.