Metabolic SyndromeJuly 2006
By Steven V. Joyal, MD
Dropping dead from a heart attack, being crippled by a catastrophic stroke, having limbs amputated as a result of peripheral vascular disease—these are among the frightening consequences of vascular disease, the number-one killer of Americans.
Metabolic syndrome and its associated condition of insulin resistance pose a major threat to cardiovascular health that most health care practitioners do not even discuss with their patients. Remarkably, the public knows very little about this silent but deadly condition, and many affected individuals are not even aware that metabolic syndrome is inflicting severe damage to their arteries and brain cells.
The news media and health care providers pay almost no attention to the epidemic of insulin resistance, the fundamental cause of metabolic syndrome.
To avoid the potentially disastrous cardiovascular consequences of metabolic syndrome, you need to understand:
Gauging Your Risk for Insulin Resistance
Metabolic syndrome is characterized by insulin resistance. Before explaining insulin resistance, we need to understand what insulin is and how it acts in the body.
A hormone produced in the pancreas, insulin’s major function is to regulate blood sugar, or glucose, levels. Insulin helps to shuttle glucose molecules from the blood into the cells of the body. When blood sugar levels increase, insulin output increases.
Insulin resistance means that insulin does not work optimally at its target tissue—such as muscle, fat, or liver tissue—to drive glucose into cells. This has numerous adverse consequences, including glucose and insulin levels that are much higher than normal. As the body attempts to overcompensate for poor insulin action by pumping out more insulin from the pancreas, insulin levels rise. Eventually, over time, the pancreas can “burn out” and no longer produce enough insulin to control blood sugar. When insulin levels are not sufficient to bring blood sugar levels down to the normal range, type II diabetes mellitus can result.
The gold standard for measuring insulin resistance is a very complex procedure called a “hyperinsulinemic euglycemic clamp” that is offered at specialized academic medical research centers. In this two-hour procedure, insulin is infused intravenously at a constant rate according to body weight. At the same time, glucose is infused intravenously at a variable rate to balance out the insulin infusion. The rate of glucose infusion into blood during the last 30 minutes of the test determines insulin sensitivity.
Fortunately, to help determine your risk of insulin resistance, you do not have to travel to an academic medical center to have the “hyper-insulinemic euglycemic clamp” performed; instead, you need only undergo some simple blood tests.
Certain blood tests such as fasting insulin can serve as surrogate markers for insulin resistance. Excess insulin (fasting hyperinsulinemia) is defined when levels equal to or greater than 15 µU/mL are found. These higher fasting insulin levels are associated with insulin resistance.1 Other blood tests that are very useful in evaluating the risk of insulin resistance include serum triglycerides and high-density lipoprotein (HDL). Triglycerides equal to or greater than 130 mg/dL and a triglyceride:HDL ratio equal to or above 3.0 suggest a high risk of insulin resistance.1 In fact, the Life Extension Foundation has consistently advocated even lower levels of triglycerides (less than 100 mg/dL) as being optimal.
Do You Have Metabolic Syndrome?
Afflicting one of every five Americans (with even higher rates in certain ethnic populations), metabolic syndrome has ominous implications for cardiovascular disease risk.2
More than 20 years ago, scientists identified the constellation of conditions that characterizes metabolic syndrome in a group of patients with a drastically elevated risk of heart disease and stroke. Initially called “Syndrome X” by scientists, it is now known as metabolic syndrome. This dangerous condition is characterized by insulin resistance, which leads to abnormally high serum lipids and cholesterol, high blood pressure, abnormally high blood sugar, and increased blood-clotting tendencies.3
Metabolic syndrome dramatically increases cardiovascular disease risk.4 Recent trial results in more than 1,200 men followed for 11 years found that those with metabolic syndrome were up to 360% more likely to die from coronary heart disease.5
The diagnostic criteria for metabolic syndrome can differ slightly depending on the medical experts consulted. A standard, accepted definition was established by the Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III).6 According to its definition, you have metabolic syndrome if you have three or more of the following criteria: