DEFINITION
Diabetes Mellitus (DM) is a group of metabolic disorder characterized by hyperglycemia and abnormalities in carbohydrate, fat, and protein metabolism. It results from defects in insulin secretion, insulin sensitivity, or both. Chronic microvascular, macrovascular, and neuropathic complication may ensue.
PATHOPHYSIOLOGY
- Type I Diabetes Mellitus accounts for 5% to 10% of all diabetes case. It generally develops in childhood or early adulthood and result from immune mediated destruction of pancreatic B-cell, resulting in an absolute deficiency of insulin. There is a long preclinical period (up to 9-13 years) marked by the presence of immune markers when B-cell destruction is thought to occur. Hyperglycemia occurs when 80% to 90% of B-cells are destroyed. There is a transient remission ("honeymoon" phase) followed by established disease with associated risk for complication and death. The factors that initiate the autoimmune process are unknown, but the process is mediated by macrophages and T lymphocytes with circulating autoantibodies to various B-cell antigens (e.g islet cell antibody, insulin antibodies).
- Type 2 Diabetes Mellitus accounts for as many as 90% of DM cases and is ussualy charactherized by the presence of both insulin resistance and relative insulin deficiency. Insulin resistance is manifested by increased lipolysis and free fatty acid production, increased hepatic glucose production, and decreased skeletal muscle uptake of glucose. B-cell dysfunction is progressive and contributes to worsening blood glucose control over time. Type 2 DM occurs when a diabetogenic lifestyle (excessive calories, inadequate exercise, and obesity) is superimposed upon a susceptible genotype. <Hg>
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