Pathophysiology
Diabetes mellitus (DM) is a group of metabolic diseases that are characterized by hyperglycemia and defects in insulin production in the pancreas and/or impaired tolerance to insulin effects. DM is a leading cause of morbidity and mortality. Because the disease can be insidious, the diagnosis is often delayed. Effects of the disease can be macrovascular, as seen in the cardiovascular system/arthrosclerosis, or microvascular, as seen with retinopathy, nephropathy, and neuropathy.
Normal glucose homeostasis is controlled by three interrelated processes. There is gluconeogenesis (glucose production that occurs in the liver), uptake and utilization of glucose by the peripheral tissues of the body, and insulin secretion by the pancreatic islet cells. What triggers the production and release of insulin from the pancreas is the presence of glucose in the body. The main function of insulin is to increase the rate of transport of glucose into certain cells of the body, such as striated muscles, fibroblasts, and fat cells. It is also necessary for transport of amino acids, glycogen formation in the liver and skeletal muscles, triglyceride formation from glucose, nucleic acid synthesis, and protein synthesis.
Insulin enters cells by first binding to target insulin receptors. DM and some of those with prediabetes have impaired glucose tolerance—in these individuals, blood glucose rises to abnormally high levels. This may be from a lack of pancreatic hormone release or failure of target tissues to respond to the insulin present or both.
Read more about this topic: Prediabetes