New Delhi, Dec. 28: Insulin is a hormone that is produced by the beta cells, which are cells that are scattered throughout the pancreas. The insulin produced is released into the blood stream and travels throughout the body. Insulin is an important hormone that has many actions within the body. Most of the actions of insulin are directed at metabolism (control) of carbohydrates (sugars and starches), lipids (fats), and proteins. Insulin also is important in regulating the cells of the body including their growth.

Insulin resistance (IR) is a condition in which the cells of the body become resistant to the effects of insulin, that is, the normal response to a given amount of insulin is reduced. As a result, higher levels of insulin are needed in order for insulin to have its effects. The resistance is seen with both the body''s own insulin (endogenous) and if insulin is given through injection (exogenous).There are probably several causes of insulin resistance and there is thought to be a strong genetic factor (an inherited component), Some medications also can lead to insulin resistance. In addition, insulin resistance is seen often in the following conditions:

· the metabolic syndrome

· obesity

· pregnancy

· infection or severe illness

· stress

· during steroid use

Type 2 diabetes is the type of diabetes that occurs later in life. Insulin resistance precedes the development of type 2 diabetes, sometimes by years. In individuals who will ultimately develop type 2 diabetes, it is believed that blood glucose and insulin levels are normal for many years; then at some point in time, insulin resistance develops.

At this point, there is often an association of high insulin levels, central obesity, cholesterol abnormalities, and /or high blood pressure (hypertension). When this constellation of disease processes occur, it is know as the metabolic syndrome.

One of the actions of insulin is to cause the cells of the body, particularly the muscle and fat cells, to remove and use glucose from the blood. This is one way in which insulin controls the level of glucose in blood. Insulin has this effect on the cells by binding to insulin receptors on the surface of the cells. You can think of it as insulin "knocking" on the doors of muscle and fat cells. The cells hear the knock, open up, and let glucose in to be used by the cell. With insulin resistance, the muscles don''t hear the knock as well (they are resistant), and the pancreas is notified that it needs to make more insulin, which increases the level of insulin in the blood and causes a louder knock.

The resistance of the cells continues to increase over time. As long as the pancreas is able to produce enough insulin to overcome this resistance, blood glucose levels remain normal. When the pancreas can no longer produce enough insulin, the blood glucose levels begin to rise, initially after meals when glucose levels are at their highest and more insulin is needed, but eventually in the fasting state too. At this point, type 2 diabetes is present.While the metabolic syndrome links insulin resistance with abdominal obesity, elevated cholesterol and high blood pressure, there are several medical other conditions that are associated with insulin resistance specifically. It may be that insulin resistance is the cause of some of these conditions, but this has not yet been proven. Conditions associated with insulin resistance include:

Type 2 Diabetes

Overt diabetes may be the first sign that insulin resistance is present. While it can be noted long before diabetes develops, in cases where there is reluctance or inability to see a physician regularly, insulin resistance can present as type 2 diabetes.

Fatty liver

Fatty liver is strongly associated with insulin resistance. The accumulation of fat in the liver is a manifestation of the disordered control of lipids that occurs with insulin resistance. Fatty liver associated with insulin resistance may be mild or severe. Newer evidence suggests that fatty liver may even lead to cirrhosis of the liver and, possibly, liver cancer.

Arteriosclerosis

Arteriosclerosis, also known as atherosclerosis, is a process of progressive thickening and hardening of the walls of medium-sized and large arteries. Arteriosclerosis is responsible for:

· coronary artery disease (angina and heart attack ),

· strokes and

· peripheral vascular disease.

Other risk factors for arteriosclerosis include:

· high levels of "bad" (LDL) cholesterol,

· high blood pressure,

· smoking,

· diabetes, and a

· family history of arteriosclerosis.

Skin Lesion

Skin lesions include increased skin tags and a condition called acanthosis nigricans - a darkening and thickening of the skin especially in fold areas such as the neckline and axilla. This condition is directly related to the insulin resistance, though the exact mechanism is not known.

· Acanthosis nigricans: Acanthosis nigricans is a cosmetic condition strongly associated with insulin resistance in which there is darkening of the skin in areas where there are creases such as the neck and arm pits.

· Skin tags: Skin tags are also seen with increased frequency in patients with insulin resistance. A skin tag is a common, benign condition which consists of a bit of skin that projects from the surrounding skin and may appear attached to the skin. Skin tags can vary quite a bit in appearance. They may be smooth or irregular, flesh colored or more deeply pigmented, and either simply be raised above the surrounding skin or have a stalk (a peduncle) so that the skin tag hangs from the skin.

Reproductive abnormalities in women

Reproductive abnormalities include difficulty with ovulation and conception (infertility), irregular menses, or a cessation of menses. In contrast, there are no known reproductive abnormalities in men with insulin resistance.

Polycystic ovary disease

Polycystic ovary disease is a hormonal problem that affects young women. It is associated with irregular periods or no periods at all, obesity, and increased growth of body hair.(ANI)