About one in three U.S. adults has metabolic syndrome—a group of conditions that together indicate higher risk for a number of serious health conditions. Knowing if you are one of them gives you a chance to avoid these negative health outcomes.
Metabolic Syndrome. Metabolic syndrome is not a disease or condition of its own, but a cluster of factors that indicate you are at increased risk for type 2 diabetes, heart disease, heart attack, stroke, and a circulation problem called peripheral vascular disease. “Metabolic syndrome is defined by some basic clinical factors your healthcare provider can measure at a regular checkup,” says Richard D. Siegel, MD, co-director of the Diabetes and Lipid Center at Tufts Medical Center. “These are blood pressure, waist circumference, and blood concentrations of fasting triglycerides, glucose, and HDL cholesterol. If any three of these five criteria are outside the desired range, you have metabolic syndrome. The more factors you have, the higher your risk for disease. Treating the conditions that make up metabolic syndrome with lifestyle changes and medications (as necessary) can help you avoid serious outcomes.”
Metabolic syndrome is increasingly referred to as insulin resistance syndrome. Insulin is a hormone produced by the pancreas that causes glucose (sugar) to move from the blood into cells where it is used for energy or stored. Sometimes the cells become resistant to insulin’s signals. “People with metabolic syndrome tend to have higher levels of insulin in their blood than people who don’t have the syndrome,” says Siegel, “even if their glucose levels are relatively normal.” This indicates insulin resistance, which is a step on the way to type 2 diabetes.
The Factors. Having any three of the five factors described in this section indicates you have metabolic syndrome and are at increased risk for type 2 diabetes, heart disease, heart attack, stroke, and peripheral artery disease. Let’s take a closer look:
1. A large waistline
Cutoff: Women—waist circumference over 35 inches. Men—waist circumference over 40 inches. “These measurements are best applied to people of European descent,” says Siegel. “People of other backgrounds, such as those of Asian heritage, may have lower cutoffs.”
Why it’s a factor: Most of our body fat is padding under the surface of our skin. Extra fat in your stomach area, however, is often an indicator of visceral fat, fat that wraps around the organs, including the liver. “Visceral fat and insulin resistance tend to go together,” says Siegel.
Research has found amount of visceral fat is correlated with the amount of fat in the liver. The liver plays an important role in regulating blood sugar levels, and fat in the liver (non-alcoholic fatty liver disease, or NAFLD) has been associated with increased risk for insulin resistance. (For more information on NAFLD, see our May 2023 issue.) Extra body fat (particularly belly fat) contributes to an increase in systemic inflammation, a factor also related to elevated risk for type 2 diabetes, heart disease, heart attack, stroke, and peripheral vascular disease.
Extra fat in your mid-section, therefore, is a bigger risk factor for heart disease and type 2 diabetes than extra fat in other parts of your body.
Diagnosis: This measure is not currently a typical part of health check-ups, but that may be changing. You can easily measure your waist circumference at home with a flexible tape measure. Place the tape measure midway between the top of your hip bone and the bottom of your ribs, in line with your belly button.
2. High blood pressure (hypertension)
Cutoff: Higher number over 130 mm Hg or lower number over 80.
Why it’s a factor: High blood pressure can damage the lining of your blood vessels, paving the way for the development of plaque, a cholesterol-rich substance that narrows and stiffens your arteries (a condition called atherosclerosis). Plaque buildup in arteries leading to the heart can cause angina (chest pain). Plaque in the arteries leading to the brain contributes to the development of dementia. When enough builds up, plaque can eventually block blood flow, causing a heart attack or stroke.
Diagnosis: A healthcare provider can take your blood pressure. Monitors are available for home use, but not all models are good choices. Ask your healthcare provider or pharmacist for advice or go to validatebp.org to find the best options.
Healthy individuals 18 to 39 years old should have their blood pressure checked at least every 3 to 5 years. Those 40 or older should be checked at least annually. If you have high blood pressure, follow the recommendation of your healthcare provider.
3. High blood sugar levels
Cutoff: Fasting blood glucose over 100 mg/dl. (This level is the start of the “prediabetes” range.)
Why it’s a factor: High blood sugar is directly related to insulin resistance. If cells become less responsive to insulin, the pancreas churns out more in an effort to get glucose into the cells that need it for energy. If there comes a time when the pancreas can’t keep up or the cells become too unresponsive, glucose builds up in the blood, leading to high blood sugar and, eventually, type 2 diabetes if the condition is not addressed with lifestyle changes.
Diabetes has a strong correlation with cardiovascular disease. Both type 1 and type 2 are known to increase risk for atherosclerosis and speed up its progression through a variety of mechanisms.
Diagnosis: Your fasting blood sugar levels should be checked regularly (once every year or two, depending on your age and other risk factors) using a blood test (this means you will need to abstain from eating or drinking anything but water for eight to 12 hours before your blood is drawn). Another measure typically tested at the same time is hemoglobin A1c (Hb A1c). This gives you and your healthcare provider an idea of your blood sugar levels over the past three months. Healthy people should have this blood test every three years or so. Those diagnosed with prediabetes should be tested at least yearly. If you have type 2 diabetes, follow the recommendations of your healthcare provider.
4. High blood triglyceride levels
Cutoff: Fasting triglyceride level of 150 mg/dL or higher.
Why it’s a factor: Triglycerides are a type of fat. They are in the foods we eat, but our body also makes triglicerides from excess calories and stores them as body fat. Refined carbohydrates particularly increase blood triglyceride levels. A high blood triglyceride level contributes to the development of atherosclerosis.
Diagnosis: Blood concentrations of triglyceride are measured as part the standard fasting blood test called a lipid panel which also measure total, LDL, and HDL cholesterol levels. Younger adults should have this blood test done every five years; men aged 45 to 65 and women aged 55 to 65 every one to two years; and adults over 65, annually.
5. Low HDL (“good”) cholesterol levels
Cutoff: Males, under 40 mg/dL. Females, under 50 mg/dL.
Why it’s a factor: Whereas “bad” low density lipoproteins (LDL) deliver cholesterol to your blood vessels, high density lipoproteins (HDL), known as “good” cholesterol, remove cholesterol from your blood vessels. Higher concentrations of HDL cholesterol in the blood are considered protective against atherosclerosis and cardiovascular disease.
Diagnosis: Like triglyceride, HDL levels are measured with a lipid panel. (See the section on triglyceride above for recommended frequency of testing.)
These conditions are all connected to each other, so when you have one, you are more likely to have or develop the others. “Having three of the five conditions counts as metabolic syndrome,” says Siegel, “but if you have two and have other risk factors, you need to consider that you may be at increased risk for cardiovascular disease and type 2 diabetes. Fat in the liver and elevations in blood levels of uric acid, leptin, or a clotting factor called PAI-1 are all minor criteria your healthcare provider may consider when evaluating your risk.”
It’s interesting to note that body mass index (BMI) is not part of metabolic syndrome. “BMI tends to track with total fat,” says Siegel, “but it may not be the best measure of risk for future disease.”
What to Do. Working on improving your diet quality, increasing physical activity, and losing excess fat can lower your chances of developing all of the factors that make up metabolic syndrome, and therefore type 2 diabetes and cardiovascular disease. These same changes can also improve each of these factors if you already have them. For ways to take action, see the Take Charge! box.