The recently completed Diabetes Control and Complications Trial (DCCT) provided compelling evidence that intensive treatment of people with insulin-dependent diabetes mellitus can delay or prevent diabetic microvascular complications. Although not studied in the DCCT, patients with noninsulin-dependent diabetes mellitus likely will benefit from near-normoglycemia. Although it is difficult to prove a similar causal relation between hyperglycemia and infection (this outcome was not looked for in the DCCT), there is substantial in vitro data and evolving clinical studies that support this hypothesis. This information is presented in this article following a review of the regulation of glucose levels.