The recent findings of the United Kingdom Prospective Diabetes Study (UKPDS) have focused attention on the need to prevent complications in type 2 diabetes mellitus. Understanding the pathogenesis and physiologic mechanisms that lead to complications in the patients with type 2 diabetes mellitus is imperative to prevent their progression and improve treatment. This article discusses the more common complications and their possible etiologies, progression, and contribution to the morbidity of the diabetic population. It also reviews treatment of these complications and recent advances. In addition, some of the less common complications will be identified so that primary care physicians and specialists will be aware and not overlook these in patients who can be treated early and aggressively.