Normally, the body uses dietary starch and sugar for energy, stores some as glycogen, and turns the rest into fat. Factors such as genetic predisposition, inactivity, and obesity can create a condition where these processes become overwhelmed. Beta cells in the pancreas secrete increased insulin in an attempt to control blood sugar, but the liver, muscles, and fat cells respond by protecting themselves from too much insulin and become resistant. Beta cells work harder and are less effective. Because insulin is a vital hormone with many functions, insulin resistance has many negative effects on health.
Hypertension
Insulin allows the body to maintain a proper balance of minerals. Magnesium increases the flexibility of blood vessels, but insulin resistance allows this valuable nutrient to be lost in the urine. At the same time, too much sodium leads to fluid retention. The effect is an elevation in blood pressure.
Osteoporosis
Insulin regulates the way growth hormone, testosterone and progesterone store protein, grow tissue and build bones. Insulin resistance impairs these processes and is responsible for an increased depletion of calcium. The effect is bone loss.
Cardiovascular Disease
In a study published in "Diabetes Care," the magazine of the American Diabetes Association, researchers found that insulin resistance influences homocysteine metabolism, allowing the amino acid to build up and damage the lining of blood vessels. Elevated levels of homocysteine are associated with an increased risk of heart attack and stroke.
Low density lipoproteins (LDL) carry fats into the arteries and deposit them there. High density lipoproteins (HDL) transport fats out of the arteries and back to the liver. Elevated insulin levels stimulate the liver to produce triglycerides, raising bad (LDL) and lowering good (HDL) cholesterol. Elevated triglycerides and low HDL levels are associated with an increased risk of heart disease and stroke.
Cancer
Too much insulin increases proliferation and inhibits the destruction of abnormal cells. In a large population-based study, researchers at the State University of New York at Buffalo found that metabolic abnormalities associated with insulin resistance produce an increased risk of colorectal cancer in both men and women. Breast cancer has also been associated with insulin resistance.
Type 2 Diabetes
Insulin resistance slowly increases until blood sugar rises out of control, resulting in the metabolic condition known as type 2 diabetes. High blood sugars in type 2 diabetes frequently coincide with high insulin levels, which are not normally tested. Doctors now strive to diagnose "pre-diabetes," a set of symptoms that include mildly elevated blood glucose. Intervention at this stage with dietary and lifestyle improvements can reverse the condition. Complications of type 2 diabetes include poor healing, nerve pain, blindness and kidney failure.
References
- National Diabetes Information Clearinghouse
- James B. Meigs, MD, MPH, et.al., Fasting Plasma Homocysteine Levels in the Insulin Resistance Syndrome, "Diabetes Care," August, 2001
- Maurizio Trevisan, et.al., Markers of Insulin Resistance and Colorectal Cancer Mortality, "Cancer Epidemiology, Biomarkers & Prevention," September, 2001, 10
