Metabolic Syndrome Features
Metabolic syndrome is diagnosed when a patient has at least 3 of the following 5 criteria: elevated waist circumference (≥102 cm in men, ≥88 cm in women), elevated triglycerides (≥150 mg/dL), low HDL cholesterol (<40 mg/dL in men, <50 mg/dL in women), elevated blood pressure (≥130/85 mmHg), and elevated fasting glucose (≥100 mg/dL). 1
Core Diagnostic Components
The five features that define metabolic syndrome are:
1. Abdominal Obesity (Central Adiposity)
- Waist circumference ≥102 cm (40 inches) in men 2, 1
- Waist circumference ≥88 cm (35 inches) in women 2, 1
- This is the cornerstone clinical feature and reflects visceral adiposity, which is highly correlated with insulin resistance 2, 3
2. Atherogenic Dyslipidemia
- Elevated triglycerides ≥1.7 mmol/L (≥150 mg/dL) 2, 1
- Low HDL cholesterol <1.03 mmol/L (<40 mg/dL) in men 2, 1
- Low HDL cholesterol <1.29 mmol/L (<50 mg/dL) in women 2, 1
- This lipid pattern includes elevated apolipoprotein B and increased small, dense LDL particles 2
3. Elevated Blood Pressure
- Systolic BP ≥130 mmHg and/or diastolic BP ≥85 mmHg 2, 1
- Alternatively, current use of antihypertensive medication qualifies 2
4. Elevated Fasting Glucose
- Fasting plasma glucose ≥5.6 mmol/L (≥100 mg/dL) 2, 1
- This includes impaired fasting glucose, impaired glucose tolerance, or established type 2 diabetes mellitus 2
5. Insulin Resistance
- While not directly measured in the diagnostic criteria, most persons with metabolic syndrome have underlying insulin resistance 2
- This contributes to the development of all other metabolic risk factors 2
Additional Pathophysiologic Features
Beyond the five diagnostic criteria, patients commonly manifest:
- Prothrombotic state: elevated plasminogen activator inhibitor-1 (PAI-1), factor VII and XII, and fibrinogen 2
- Proinflammatory state: elevated inflammatory markers reflecting vascular inflammation 2, 4
- Platelet hyper-reactivity: contributing to increased atherothrombotic risk 2
Clinical Significance
Patients with metabolic syndrome have a 2-fold increased risk of developing cardiovascular disease over 5-10 years compared to individuals without the syndrome. 2, 1
The syndrome confers a 5-fold increased risk for developing type 2 diabetes mellitus. 2, 1
Diagnostic Approach
The American Heart Association criteria do not require any single factor to be present—diagnosis is made when any 3 of the 5 features are present 2, 1. This differs from earlier WHO criteria that required evidence of insulin resistance plus 2 additional factors 2.
The International Diabetes Federation initially made abdominal obesity mandatory, but later harmonized recommendations dropped this requirement, allowing any 3 of 5 components to qualify for diagnosis 2, 1.