A privately owned, obese, adult female raccoon (Procyon lotor) presented with polyuria, polydipsia, weight loss, and increased appetite. Diabetes mellitus was diagnosed based on laboratory findings, including hyperglycemia and glucosuria. As a result of the raccoon's age and obesity at the onset of clinical signs, the raccoon was thought to have type 2 diabetes mellitus, a diagnosis that was supported by paired glucose tolerance tests. Treatment consisted of dietary management and daily insulin therapy. The raccoon was gradually weaned off insulin with no return of clinical signs, further verifying the characterization of type 2 diabetes mellitus.