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Diabetes mellitus, a term that means “the running through of sugar,” was first identified in the 1st century AD.(1) The disease was described in historical text as “the melting down of flesh into urine.” Diabetes mellitus is a chronic condition of insufficient insulin availability in relation to need. This can represent an absolute insulin deficiency, impaired insulin secretion, defective insulin receptors on target cells, or insulin that is inactivated before it is able to function. Diabetes mellitus is a disease in which the body does not produce or does not use insulin effectively. It is not simply hyperglycemia.
Insulin is a hormone produced in the pancreas by the beta cells in the Islets of Langerhans. Insulin secretion is regulated by blood glucose levels. It is responsible for transporting glucose (from carbohydrates) into the cells to fuel cellular metabolism and energy production. After a meal, when blood sugar increases, insulin levels rise. Between meals, when blood sugar is low, insulin levels remain low. Insulin is secreted from the pancreas directly into the liver where some is utilized and some is degraded. The rest is released into the general circulation. By facilitating the transport of glucose into the cells, insulin reduces blood sugar. Insulin also decreases the catabolism of fat stores and stimulates triglyceride synthesis. Insulin is involved in the active transport of amino acids into the cell, increasing protein synthesis. The growth and development of children is dependent on insulin.
Diabetes can affect people of any age. It increases the risk of chronic, debilitating conditions, including cardiovascular disease, retinopathy and blindness, peripheral neuropathies, vascular insufficiency and amputation, immune deficiencies, skin ulceration and wound healing disturbances, and kidney disease. The discovery of insulin in the early 20th century has afforded much progress in the diagnosis and treatment of the disease.
Diabetes is diagnosed when there is a fasting plasma glucose (FPG) of greater than 126mg/dL, or a two-hour plasma glucose (OGTT – oral glucose tolerance test) of greater than 200mg/dL. There are two forms of diabetes mellitus recognized today: type 1 (formerly referred to as IDDM, insulin dependent diabetes mellitus, or juvenile onset) and type 2 (previously called NIDDM, non-insulin dependent diabetes, or adult onset).
Ninety percent of individuals with diabetes have type 2. Most of these individuals are over 40 years old. One in five patients is over the age of 65, and 80 percent are overweight.(2) In fact, a 16 year study of over 80,000 individuals, found that overweight or obesity is the single most important predictor for this disease.(3) Many patients have elevated blood sugar levels seven to ten years before symptoms occur.
When blood sugar regulation is impaired, despite the availability of insulin, type 2 diabetes is suspected. Type 2 diabetes is characterized by elevated blood sugar and impaired insulin response. It is a non-ketotic form of diabetes. People with type 2 are not dependent on insulin to survive. The pathophysiology of type 2 diabetes is not fully understood. Three physiological abnormalities typically occur in type 2: insulin resistance, increased glucose production in the liver (hepatic gluconeogenesis), and poor beta cell function. These can occur individually or in combination.
Insulin resistance appears to be the first stage of the disease. It is defined as an inability of insulin to facilitate glucose uptake from the blood into the cells.(4) In fact, a 16 year study of over 80,000 individuals, found that overweight or obesity is the single most important predictor for this disease.(3) It is characterized by poor insulin binding at the receptor cells, particularly skeletal muscle cells. While the beta cells are able to re
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