Although medical science has studied insulin resistance since the 1960s, recent research indicates that insulin resistance may have a bigger impact on health than once thought. This brochure provides answers to questions about insulin resistance, its impact on health, and dietary management.
What is Insulin?
Insulin is a hormone secreted by the pancreas. It helps the body utilize blood glucose or "blood sugar." Insulin does so by binding with receptors on cells like a key would fit into a lock. Once the key insulin has unlocked the door, the glucose can pass from the blood into the cell. Inside the cell, glucose is either used for energy or stored for future use in the form of glycogen.
What is Insulin Resistance?
Insulin resistance occurs when the normal amount of insulin secreted by the pancreas is not able to "unlock the door" to cells. To compensate, the pancreas secretes additional insulin. When the body's cells resist or do not respond to even high levels of insulin, glucose builds up in the blood resulting in high blood sugar. Even people with diabetes who take oral medication or insulin injections to control their blood glucose levels, can have higher than normal blood insulin levels due to insulin resistance.
Why is Insulin Resistance in the News?
More and more people in the U.S. are becoming obese, physically inactive, or both. Obesity and physical inactivity aggravate insulin resistance. Also, people who are insulin resistant typically have an imbalance in their blood lipids. They have an increased level of triglycerides (fat) and a decreased level of HDL ("good") cholesterol. Imbalances in total fat and HDL cholesterol increase the risk for heart disease. These findings have heightened awareness of insulin resistance and its impact on health.
Who has Insulin Resistance?
Almost all individuals with Type II diabetes mellitus ("diabetes") and many with hypertension, cardiovascular disease, and obesity are insulin resistant. These diseases and conditions are predominantly found in countries with improved economic status such as the U. S. And in the U.S., these diseases and conditions are among the leading contributors to morbidity and mortality. Also, about 20 - 25% of the "healthy" population may be insulin resistant.
What are the Symptoms of Insulin Resistance?
There are no outward physical signs of insulin resistance. A glucose tolerance test, during which insulin and blood glucose is measured, can help determine if someone is insulin resistant. Many people who are insulin resistant produce large enough quantities of insulin to maintain near-normal blood glucose levels.
What Causes Insulin Resistance?
No one knows for sure. Some scientists think a defect in specific genes may cause insulin resistance and Type II diabetes. Researchers continue to investigate the cause. What we do know is that insulin resistance is aggravated by obesity and physical inactivity - both of which are increasing in the U.S.
Do All People with Insulin Resistance Develop Diabetes?
No. Science has not yet determined why some people with insulin resistance eventually develop diabetes and others do not. By maintaining an appropriate weight and a physically active lifestyle many individuals are able to reduce their chances of becoming insulin resistant and developing diabetes.
What is Syndrome X?
Syndrome X is a cluster of risk factors for heart disease associated with insulin resistance. These risk factors include: hypertriglyceridemia, low HDL-cholesterol, hyperinsulinemia, often hyperglycemia, and hypertension. This cluster of risk factors for heart disease has been labeled Syndrome X.
What is the Best Diet for People with Insulin Resistance?
Research indicates that low fat diets may aggravate the effect of insulin resistance on blood lipids. Therefore, for individuals who are insulin resistant, a diet low in saturated fat (less than 10 percent of total calories) and more moderate in total fat content (30 percent - 35 percent of total calories) may be beneficial. This recommendation is different from the low-fat, high-carbohydrate diet that many health organizations recommend to help prevent heart disease. Specifically, they recommend decreasing fat intake to less than 30 percent of calories. Some groups recommend even lower levels of dietary fat.
It is also beneficial to maintain an appropriate body weight since obesity can aggravate insulin resistance. To maintain an appropriate weight, regulate caloric intake and maintain a physically active lifestyle. A registered dietitian can assist with developing a proper meal plan for people with insulin resistance.
Terms & Definitions:
- Blood Glucose
- - Sugar in the blood stream that is used by the body for energy or stored as glycogen for future energy needs.
- Blood Lipids
- - Fat that is present in the blood stream, includes triglycerides and cholesterol.
- Glycogen
- - Storage form for glucose in the body.
- Insulin
- - Hormone produced by the pancreas; essential for proper use of glucose in the body.
- Insulin resistance
- - Insulin resistance occurs when the normal amount of insulin secreted by the pancreas is not able to remove glucose from the blood into the muscle cells for use as energy or storage for future use.
- Pancreas
- - Organ in the body that produces the hormone insulin.
- Type II diabetes mellitus
- - Often referred to as adult onset diabetes or noninsulin dependent diabetes mellitus. Disease state in which glucose is not able to move efficiently from the blood to the muscle cells. There are two possible causes. First, the pancreas produces enough insulin but the insulin is not effective in removing glucose from the blood. Second, the pancreas eventually may not produce enough insulin to properly remove glucose from the blood.
