In a landmark study, the Diabetes Control and Complications Trial proved that intensive insulin therapy (IIT) reduced the incidence and severity of the microvascular complications of insulin-dependent diabetes mellitus. Retinopathy, nephropathy, and neuropathy were all improved by IIT, The trial was conducted by endocrinologists experienced in the management of IIT. However, only a small minority of patients with diabetes are cared for by endocrinologists; the vast majority receive their care from primary care physicians. In this article, the authors describe the practical aspects of IIT for those physicians unfamiliar with IIT but who want to offer the benefits of this therapy to patients with diabetes. The authors define suitable candidates for IIT, describe the initiation and management of IIT, and emphasize the potential complications of this therapy, Severe hypoglycemia is the major risk of IIT, and caution must be used to reduce the incidence of this dangerous complication.