Metabolic Syndrome

Definition and PathogenesisTop

The co-occurrence of cardiovascular risk factors including central obesity, elevated blood pressure, dyslipidemia (high triglyceride and low high-density lipoprotein cholesterol [HDL-C] levels), and hyperglycemia is known as the metabolic syndrome. The pathophysiology behind the metabolic syndrome has been traditionally ascribed to insulin resistance; however, genetic predisposition and our contemporary “obesogenic” environment (ie, nutrient composition, high-calorie diets, decreased energy expenditure) are also major determinants in its development.

DiagnosisTop

According to the 2009 joint statement of International Diabetes Federation; National Heart, Lung, and Blood Institute; American Heart Association; World Heart Federation; International Atherosclerosis Society; and International Association for the Study of Obesity, the diagnosis of metabolic syndrome is made in patients who fulfill any 3 of the following 5 criteria:

1) Increased waist circumference/abdominal obesity (depending on the country of origin and ethnicity):

a) European, Middle East, Mediterranean, and sub-Saharan African population: ≥80 cm in women and ≥94 cm in men.

b) South Asian, Chinese, and ethnic Central and South American population: ≥80 cm in women and ≥90 cm in men.

c) Japanese population: ≥90 cm in women and ≥85 cm in men.

d) United States and Canada population: ≥102 cm in men and ≥88 cm in women.

2) Serum triglyceride levels >1.7 mmol/L (150 mg/dL) or current treatment for this type of dyslipidemia.

3) Serum HDL-C levels <1.0 mmol/L (40 mg/dL) in men and <1.3 mmol/L (50 mg/dL) in women or current treatment for this type of dyslipidemia.

4) Systolic blood pressure ≥130 mm Hg and/or diastolic blood pressure ≥85 mm Hg, or current antihypertensive treatment.

5) Fasting plasma glucose levels ≥5.6 mmol/L (100 mg/dL) or pharmacotherapy for elevated blood glucose levels.

The dominant feature of the metabolic syndrome is abdominal obesity with visceral fat deposition. The second most frequent feature is hypertension (patients with early metabolic syndrome may only have an altered circadian blood pressure rhythm with no blood pressure drop at night). Untreated metabolic syndrome leads to overt type 2 diabetes mellitus (if not present already) and premature atherosclerosis.

TreatmentTop

Reduction of cardiovascular risk is the rationale behind treatment of the metabolic syndrome. Consequently, the cornerstone treatment for any component of the metabolic syndrome is lifestyle modification (diet [low-calorie, low glycemic index/load, high-fiber, DASH, Mediterranean] and exercise) including weight reduction.Evidence 1Strong recommendation (benefits clearly outweigh downsides; right action for all or almost all patients). Moderate Quality of Evidence (moderate confidence that we know true effects of the intervention). Quality of Evidence lowered due to the lack of blinding. Estruch R, Ros E, Salas-Salvadvó J, et al; PREDIMED Study Investigators. Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J Med. 2013 Apr 4;368(14):1279-90. doi: 10s.1056/NEJMoa1200303. Epub 2013 Feb 25. Erratum in: N Engl J Med. 2014 Feb 27;370(9):886. PubMed PMID: 23432189. Azadbakht L, Mirmiran P, Esmaillzadeh A, Azizi T, Azizi F. Beneficial effects of a Dietary Approaches to Stop Hypertension eating plan on features of the metabolic syndrome. Diabetes Care. 2005 Dec;28(12):2823-31. PubMed PMID: 16306540. Treatment of any of the individual components is no different from treatment related to the metabolic syndrome.