Aging is associated with changes in body composition, including both fat gain and muscle loss beginning in middle age, and is associated with increased risk of type 2 diabetes. Moreover, changes in fat distribution take place in adults as they age and may contribute to the increased risk of type 2 diabetes. Recent literature has shown differences in the age-related changes in body composition by diabetes status suggesting that some of these changes might not only be a risk factor of the development of diabetes but could also be a consequence of the disease. In this article, we review the current evidence on body composition changes that take place in adults after the diagnosis of type 2 diabetes and compare them to those observed in adults without diabetes as they age. We also review the effect of various lifestyle, pharmacological, and surgical treatments that lower blood glucose on body composition in adults with type 2 diabetes.