What Is It?

Diabetes mellitus, usually called just diabetes, is a common disorder that affects the way the body processes and uses carbohydrates, fats and proteins. Each of these nutrients is a source of glucose (sugar), which is the most basic fuel for the body. The most obvious sign of diabetes is a high level of sugar in the blood.

Glucose enters body cells with the help of a hormone called insulin, which acts like a gatekeeper. Without insulin, which is produced by the pancreas, glucose cannot pass through the cell wall, and the cell must rely on less efficient fuels for energy. Type 2 diabetes occurs when your body's cells do not react efficiently to insulin produced by the pancreas, a condition called insulin resistance. In people with insulin resistance, the pancreas at first manufactures extra insulin to maintain a normal blood sugar. Eventually, as the body's insulin resistance progresses, the pancreas is unable to keep up with the demand for more and more insulin, and blood glucose levels rise.

About 95% of people with diabetes have type 2 diabetes, also called adult-onset diabetes or non-insulin-dependent diabetes. Type 2 diabetes runs in families, and it most often affects people who are older than 40. With the rise in obesity that has been seen in the United States in the last decade, type 2 diabetes increasingly is being seen in younger people, particularly African-Americans, Hispanics, and American Indians. Obesity, especially in the abdomen and at the waistline, greatly increases the risk of diabetes.

Diabetes with insulin resistance (type 2 diabetes) is one of several conditions that are known as metabolic syndrome when they occur together.

Metabolic syndrome, originally called syndrome X, is a set of problems that increase the risk of heart disease and stroke. The conditions that combine together to create metabolic syndrome include obesity, insulin resistance with elevated blood sugar, increased blood levels of insulin (hyperinsulinemia), high blood pressure, elevated levels of triglycerides, and low levels of high-density lipoprotein (HDL) cholesterol (the "good" cholesterol). These problems commonly occur together and are related to each other by a genetic or metabolic link. Both the metabolic syndrome and type 2 diabetes increase the risk of heart disease, stroke and peripheral artery disease.