The stomach is commonly the source of chronic digestive symptoms in patients with diabetes mellitus; erratic stomach emptying may result in poor glycemic control. On the other hand, medications that mimic or enhance the function of the endogenous incretins retard gastric emptying to enhance glycemic control. In patients with obesity and type 2 diabetes, bariatric procedures alter food intake and weight; however, effects on glycemic control precede and are out of proportion with the degree of weight loss. The mechanisms responsible for the improved glycemic control after bariatric surgery are the subject of ongoing research, and include increased circulating incretins stimulated by the delivery of nutrients to the intestine, contributing to weight loss and independently to glycemic control. The stomach is not always a villain, but is an ally in patients with type 2 diabetes.