1. David W. Cooke, MD* 2. Leslie Plotnick, MD† 1. *Associate Professor, Department of Pediatrics, Division of Pediatric Endocrinology, Johns Hopkins University School of Medicine, Baltimore, Md 2. †Professor, Department of Pediatrics, Division of Pediatric Endocrinology, Johns Hopkins University School of Medicine, Baltimore, Md After completing this article, readers should be able to: 1. Describe the pathogenesis of type 1 diabetes. 2. Identify acute and chronic complications of type 1 diabetes. 3. Discuss management options and treatment goals for type 1 diabetes. Diabetes mellitus is a disorder of the metabolic homeostasis controlled by insulin, resulting in abnormalities of carbohydrate and lipid metabolism. Type 1 diabetes (also called juvenile-onset diabetes mellitus and insulin-dependent diabetes mellitus) is caused by an absolute insulin deficiency, the result of a loss of the insulin-producing beta cells of the pancreas. Type 2 diabetes mellitus is characterized by two underlying defects. The earliest abnormality in an individual who develops type 2 diabetes mellitus is insulin resistance, which initially is compensated for with an increase in insulin secretion. Type 2 diabetes mellitus then develops due to a defect in insulin secretion that prevents such secretion from matching the increased requirements imposed by the insulin-resistant state. Thus, diabetes mellitus always is caused by insulin deficiency: in type 1 diabetes mellitus, the deficiency is absolute; in type 2 diabetes mellitus, the deficiency is relative. Although the percentage of cases of diabetes in children and adolescents caused by type 2 diabetes has risen in the past 1 to 2 decades, type 1 diabetes remains the most common form of diabetes mellitus in children. Recombinant insulin analogs, insulin pumps, and newer devices for home monitoring have drastically improved the ability to control glucose concentrations in patients who have diabetes. However, the feedback control in the healthy state that allows minute-to-minute regulation of insulin secretion cannot be recapitulated with current diabetes therapies, making full metabolic normalization not yet possible. Thus, some degree of hyperglycemia persists in virtually all patients who have diabetes. Long-term complications, including renal failure, retinopathy, neuropathy, and cardiovascular disease, are related to and likely caused by the …