Causes

Your body changes much of the food you eat into glucose, a type of sugar, which is then carried by the bloodstream to be used to power the millions of cells in your body. The cells cannot use glucose for energy without the help of insulin, a hormone made by the pancreas that helps glucose enter them. Diabetes is a disease in which the body's insulin-producing system malfunctions. Glucose then builds up to excessive levels in the bloodstream.

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In type 2 diabetes, which used to be called adult-onset or non-insulin-dependent diabetes, the body produces insulin but either does not produce enough to properly convert food into energy or is not able to use the insulin it does make. This form of diabetes usually occurs in people who are over 40, overweight, and have a family history of diabetes. (In type 1 diabetes, which used to be called juvenile-onset or insulin-dependent diabetes, the body completely stops producing insulin. People with Type I diabetes must take daily insulin injections to survive. This form of diabetes usually develops in children or young adults but can occur at any age.)

In some people with type 2 diabetes, the body fails to produce enough insulin to meet their needs, and glucose that can't get into the cells builds up in the bloodstream. In many others, the pancreas is actually producing more insulin than would normally be needed to convert the food they've eaten into energy; because their cells are resistant to the effects of insulin in the bloodstream, the cells don't become unlocked and allow in enough of the glucose in the blood.

Scientists don't know exactly what causes this insulin resistance, and many expect that there are several different defects in the process of unlocking cells that cause insulin resistance. Medications for type 2 diabetes focus on different parts of this insulin-cell interaction to help improve blood glucose control. Some medications stimulate the pancreas to produce more insulin. Others improve how the body uses insulin by working on insulin resistance. Physical activity also seems to lessen insulin resistance.