A condition in which the body needs extra insulin to maintain normal blood sugar levels. Along with abnormal insulin secretion, it is a hallmark of Type 2 diabetes.
Ordinarily, insulin prods the liver to decrease its production of glucose. It also helps the body’s fat and muscle tissues use glucose in the blood for energy. Insulin resistance generally takes two forms: the liver may produce too much glucose, or the body’s tissues may not use glucose from the blood efficiently.
Insulin resistance can occur even before someone develops Type 2 diabetes. In the early stages, the pancreas secretes extra insulin to compensate for insulin resistance, so blood glucose levels remain in the normal range. Eventually, the pancreas may be unable to keep up with this extra demand, blood glucose levels may begin to rise, and Type 2 diabetes may develop. A growing body of research suggests that any degree of insulin resistance can increase a person’s risk of heart disease, even if the person does not have Type 2 diabetes.
Some oral pills used to treat Type 2 diabetes, including glyburide (brand names Micronase, DiaBeta, and Glynase), glipizide (Glucotrol, Glucotrol XL), glimepiride (Amaryl), and repaglinide (Prandin), lower blood glucose levels by boosting insulin secretion. Others work by helping the body to overcome insulin resistance. Metformin (Glucophage) works primarily by decreasing the liver’s glucose production. Pioglitazone (Actos) and rosiglitazone (Avandia) work primarily by making muscle and fat tissues more responsive to insulin, so that they use glucose more readily. Weight loss and exercise, which have long been known to reduce the risk of Type 2 diabetes, appear to help fight insulin resistance as well.