What is insulin resistance?

Insulin is one of the body’s hormones that controls blood glucose. Normally, when the body senses a higher glucose level, insulin is released to lower the level of glucose. But with insulin resistance, the body steadily becomes less responsive to the actions of insulin. Despite the high levels of insulin, the blood sugar levels rise, and eventually type 2 diabetes results.

People who are insulin resistant tend to gain belly fat—with increasing waistlines (the apple shape as opposed to the pear shape). These individuals also have elevated triglycerides, low HDL cholesterol, high blood pressure, and high blood glucose levels.

The main causes of type 2 diabetes are:

- a condition called insulin resistance
- not making enough insulin to overcome insulin resistance

When you have insulin resistance, your body has trouble using insulin. Your cells resist using insulin so glucose cannot get into your cells. Your blood glucose becomes high. Your pancreas tries to keep blood glucose normal by making more insulin. At first this helps, but eventually your cells make less and less insulin. At the same time, your cells become even more resistant to insulin.

Insulin resistance occurs when the body can't use insulin efficiently. To compensate, the pancreas releases more and more insulin to try to keep blood sugar levels normal. Gradually, the insulin-producing cells in the pancreas become defective and ultimately decrease in number. As a result, blood sugar levels begin to rise, causing full-blown diabetes to develop. Insulin resistance may be linked to obesity, hypertension and high levels of fat in the blood.

Insulin resistance is a term to describe a malfunction in the body that prevents insulin from working properly. Produced by the pancreas, insulin is a key molecule that enables glucose, one of the body’s fuel sources, to enter the cells. In a person with diabetes, several malfunctions may occur at the same time. As a result, the glucose level in the blood remains high. The pancreas, thinking the glucose has been absorbed, secretes more insulin, which causes the body’s insulin level to remain high as well. Insulin resistance can be a warning of pre-diabetes or diabetes developing.

For reasons that aren't well understood, in some people, particularly the sedentary and overweight, insulin doesn't function properly; it seems that in these individuals, the cells themselves somehow become resistant to the action of insulin, so the insulin can't mediate the processes that make the glucose available to the tissues that need it. The result is that tissues starve for energy, even though ample fuel is available.

As the cells become resistant to the action of insulin and blood glucose levels rise, the body secretes more insulin in a futile effort to get energy to the cells, resulting in hyperinsulinemia. Researchers have recently found that hyperinsulinemia reduces secretion of sodium from the body, increasing blood volume and thus the risk of high blood pressure (hypertension or HTN) and the host of health problems that result, including increased risk of heart disease, kidney disease, and stroke. Hyperinsulinemia also triggers the nervous system to narrow blood vessels and causes vessel walls to thicken, making it more difficult for blood to flow through the vessels, further predisposing victims to HTN and increasing the strain on the heart. It also appears that insulin resistance is the condition underlying high levels of triglycerides and decreased levels of HDL or "good" cholesterol in the blood, both predictors of CVD, although the precise mechanism is not clear.

Insulin resistance is a condition common in type-2 diabetics in which the body produces large volumes of insulin, but cannot use it properly.

Insulin resistance is at the heart of a number of serious health conditions, including obesity and diabetes. To learn what insulin resistance is, watch this video featuring family physician and Dr. Oz guest Dr. Mark Hyman.

Insulin resistance is a condition in which body cells do not fully respond to the action of insulin, a hormone that controls the amount of sugar (glucose) in the blood. As a result, blood sugar levels become abnormally high. Over time, insulin resistance can result in consistently high blood sugar levels, which increases a person's risk for type 2 diabetes. Pregnant women who are insulin resistant have an increased risk for gestational diabetes. Usually, insulin resistance develops in people who are overweight and not physically active. These characteristics are often associated with having high cholesterol and high blood pressure. People who are insulin resistant have an increased risk of heart disease and stroke, especially if other risk factors, such as being a smoker or having high cholesterol levels, are present.