Metabolic Syndrome

(Syndrome X; Insulin Resistance Syndrome; Deadly Quartet)

by Amy Scholten, MPH

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Definition | Causes | Risk Factors | Symptoms | Diagnosis | Treatment | Prevention

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What is Metabolic Syndrome?

Definition

Metabolic syndrome is a group of risk factors. The factors are related to the breakdown and use of food. These conditions are risk factors for health issues such as:

• Diabetes
• Coronary heart disease
• Stroke
• Peripheral vascular disease

In general, it is characterized by:

• Abdominal obesity-high amount of fat in trunk area
• Dyslipidemia -high triglycerides and low high-density lipoprotein (HDL, or 'good') cholesterol
• High blood pressure
• Insulin resistance (glucose intolerance or prediabetes)-insulin helps move glucose out of the blood into cells; if a resistance develops it will increase the amounts of blood glucose

Causes

The exact cause of metabolic syndrome is not known. It believed to be due to a combination of factors, such as:

• Genetic factors
• Insulin resistance
• Obesity -especially central obesity, in core of body
• Lack of physical activity
• Poor diet
• Fatty tissue abnormalities linked to insulin resistance and obesity
• Psychological stress
• Chronic low-grade inflammation
• Aging

Risk Factors

Risk factors for metabolic syndrome include the following:

• Overweight (especially excessive fat in the abdominal region)
• Poor diet
  • Eating a diet high in calories, sugar, saturated fats, and starchy foods (eg, bread, cereal, rice, pasta, potatoes), and low in dietary fiber
  • Drinking a lot of soda, even diet soda, has been linked to metabolic syndrome
• Sedentary lifestyle
• Gender
  • No difference in Caucasians
  • African Americans: females more than males by 57%
  • Mexican Americans: females more than males by 26%
• Genetics: family history of diabetes, lipid disorders, high blood pressure, or heart disease
• Socioeconomic factor with high incidence in low household income families
• Age: over 60 years old
• Ethnicity: Latino/Hispanic American, African American, Native American, Asian American, Pacific Islander
• History of glucose intolerance or gestational diabetes
• A diagnosis of any of the following conditions:
  • High blood pressure
  • Elevated triglycerides/low HDL-cholesterol
  • Cardiovascular disease
  • Polycystic ovary syndrome
  • Acute pancreatitis
  • Chronic kidney disease

Symptoms

Except for obesity, there are no obvious symptoms. Those who are obese may have the following symptoms and signs:

• Sleep apnea
• Back or knee pain
• Shortness of breath
• Reduced exercise tolerance
• Fatigue
• Central obesity
• Elevated blood pressure

Diagnosis

The doctor will ask about your medical history. A physical exam will be done.

Your doctor may order lab tests such as:

• Blood tests to measure:
  • Fasting blood sugar levels (glucose) or a two-hour post-glucose challenge blood sugar level
  • Fasting insulin
  • Triglyceride level
  • HDL cholesterol level
• C Reactive Protein, especially highly sensitive CRP
• Blood pressure
• Calculation of body mass index (BMI) from weight and height
• Calculation of the 10 year risk of cardiovascular disease

You may be diagnosed with metabolic syndrome if you have at least three of the following measures:

• Waist measurement-greater than 40 inches in Caucasian men (35 inches in Asian men) or 35 inches in Caucasian women (30 inches in Asian women)
• Fasting blood sugar (glucose)-greater than or equal to 100 mg/dL* (5.55 mmol/L)
• Serum triglycerides-greater than or equal to 150 mg/dL (1.7 mmol/L)
• Serum HDL ('good') cholesterol-less than 40 mg/dL (1.0 mmol/L) in men and less than 50 mg/dL (1.3 mmol/L) in women
• Blood pressure-greater than or equal to 130/85 millimeters of mercury (mm Hg)

*mg/dL = milligrams per deciliter blood, mmol/L = millimoles per liter blood

Treatment

The treatment of metabolic syndrome involves two parts:

• Treatment of underlying causes
• Treatment of specific metabolic abnormality

Prevention

To help prevent metabolic syndrome:

• Achieve and maintain a healthful weight.
• Do 30 minutes of moderate aerobic exercise at least four days per week.
• See your doctor regularly.

In addition, other unhealthy lifestyle factors also contribute to heart disease, stroke, and peripheral vascular disease. To lower your risk of these diseases:

• Eat a healthful diet. It should be low in saturated and trans fats. Also keep it low in cholesterol. Aim for a diet that is rich in whole grains, fruits, and vegetables. Avoid soda. Ask your doctor if the Mediterranean diet is right for you.
• If you smoke, quit.
• Drink alcohol in moderation only.

RESOURCES:

American Heart Association
http://www.americanheart.org

National Institute of Diabetes & Digestive & Kidney Diseases
http://www.niddk.nih.gov

CANADIAN RESOURCES:

Canadian Cardiovascular Society
http://www.ccs.ca/home/index_e.aspx

Canadian Diabetes Association
http://www.diabetes.ca/

REFERENCES:

Cornier MA, Dabelea D, Hernandez TL et al: the metabolic syndrome. Endocr Rev. 2008;29:777-822.

Deen D. Metabolic syndrome: time for action. Am Fam Physician . 2004;69:2875-2882.

Eckel RH, Grundy SM, Zimmet PA. The metabolic syndrome. Lancet . 2005;365:1415-1428.

Findings and recommendations from the American College of Endocrinology on the insulin resistance syndrome. American Association of Clinical Endocrinologists website. Available at: http://www.aace.com . Accessed January 17, 2003.

Gami AS, Witt BJ, Howard DE, et al. Metabolic syndrome and risk of incident cardiovascular events and death. J Am Coll Cardiol . 2007;49:403-414.

Grundy SM, Brewer HB, Cleeman JI, et al. American Heart Association, NHLBI. Definition of metabolic syndrome: report of the NHLBI/AHA conference on scientific issues related to definition. Circulation . 2004;109:433-438.

Grundy SM, Cleeman JI, Diniels SR, et al. AHA/NHLBI Diagnosis and management of the metabolic syndrome: an AHA/NHLBI Scientific Statement. Circulation . 2005;112:2735-2752.

Metabolic syndrome. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php . Updated May 2009. Accessed May 18, 2009.

National Heart, Lung, and Blood Institute. Available at: http://www.nhlbi.nih.gov .

National Institute of Diabetes & Digestive & Kidney Diseases. Available at: http://www.niddk.nih.gov .

Reaven GM. The metabolic syndrome or the insulin resistance syndrome? Different names, different concepts, and different goals. Endocrinol Metab Clin North Am . 2004; 33: 283-304.

Steinberger J, Daniels SR, Eckel RH et al: AHA scientifc statement: progress and challenges in metabolic syndrome in children and adolescents. Circulation. 2009;119:628-647.

Syndrome x or metabolic syndrome. American Heart Association website. Available at: http://www.americanheart.org . Accessed January 17, 2003.

Wright Jr JT, Harris-Haywood S, Pressel S, et al. Clinical outcomes by race in hypertensive patients with and without the metabolic syndrome (ALLHAT). Arch Int Med. 2008;168:207-217.

¹1/13/2009 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed/what.php : Salas-Salvadó J, Fernández-Ballart J, Ros E, et al. Effect of a Mediterranean diet supplemented with nuts on metabolic syndrome status: one-year results of the PREDIMED randomized trial. Arch Intern Med. 2008;168:2449-2458.

²2/17/2009 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed/what.php : Davidson LE, Hudson R, Kilpatrick K, et al. Effects of exercise modality on insulin resistance and functional limitation in older adults: a randomized controlled trial. Arch Intern Med. 2009;169:122-131.

³5/11/2009 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed/what.php : Nettleton JA, Lutsey PL, Wang Y, Lima JA, Michos ED, Jacobs DR. Diet soda intake and risk of incident metabolic syndrome and type 2 diabetes in the Multi-Ethnic Study of Atherosclerosis (MESA). Diabetes Care. 2009;32:688-694.

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Last reviewed February 2009 by David Juan, MD
Last Updated: 5/11/2009