Diabetes is a chronic disease in which the body makes little or no insulin, or is unable to use the insulin it makes. Insulin is a hormone produced by the pancreas that helps your body use the energy from sugar, starches, and other foods. When insulin is absent or ineffective, blood sugar (glucose) levels become higher than normal. Over time, high blood sugar levels can damage blood vessels and nerves, and lead to serious health problems such as blindness, kidney failure, heart attack, and stroke.
Type 2 diabetes, previously called adult-onset diabetes or noninsulin-dependent diabetes mellitus (NIDDM), accounts for 90% of diabetes cases. While it tends to develop gradually after the age of 40, type 2 diabetes is now being diagnosed in many overweight children and young adults, and is beginning to reach epidemic proportions.
Type 2 diabetes is associated with high levels of harmful blood fat (LDL cholesterol) and high blood pressure. The high blood glucose levels seen in type 2 diabetes cause high levels of a harmful blood fat (LDL cholesterol) and low levels of the good kind of blood fat (HDL cholesterol). This imbalance of cholesterol can lead to hardened arteries (atherosclerosis), which causes poor circulation and various other complications. Type 2 diabetes is also associated with high blood pressure.
Type 2 diabetes occurs when your body responds inefficiently to the hormone insulin, which regulates blood sugar Figure 01. Insulin is secreted by the pancreas. Normally, when insulin interacts with cells, it starts a chain reaction that ends when simple sugar (glucose) from digested carbohydrates enters cells from the bloodstream and is turned into energy or fat.
People with type 2 diabetes have cells that don't respond effectively to insulin. As a result of this inability to use insulin, glucose in the bloodstream goes unused, and can build to dangerous levels. This insulin resistance is pronounced in people with type 2 diabetes who are overweight or obese. Over time, type 2 diabetics may progress from having adequate or even greater than adequate amounts of insulin to insulin deficiency, as the insulin-producing cells in the pancreas “burn out.” This is why type 2 diabetics have blood sugar levels that become more difficult to control, and require increasing medication with time.
Insulin resistance can be inherited, or can develop as a consequence of lifestyle. Twin studies show that diabetes is an inherited disorder; however, the genetic pattern of inheritance is not yet fully understood.
Being overweight, having poor eating habits, and living a sedentary lifestyle also contribute to the risk of developing diabetes.
Figure 01. Cellular mechanisms of diabetes (animation and audio)
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