Over 1.5 billion adults worldwide are classified as either overweight or obese, with rates continuing to increase. Obese individuals are at an increased risk for multiple disease processes, particularly type-2 diabetes mellitus (T2DM). Obesity has a strong association with insulin resistance, hyperinsulinemia and glucose intolerance. Adiposity, both subcutaneous and visceral, has been proposed to contribute to insulin resistance, eventually leading to T2DM. Strong evidence exists, in both genders, for the increased glucose intolerance and incidence of T2DM with increasing weight gain. Conversely, weight loss is associated with improvement of glycemic control, insulin resistance and T2DM. Bariatric surgery has risen as a therapeutic option that provides exceptional reduction in overall weight and resolution of T2DM. However, bariatric surgery serves as one component of a multifaceted weight management strategy that is required for long-term success.