Diagnostic Criteria for Metabolic Syndrome
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
The Five Diagnostic Components
1. Central Obesity (Abdominal Circumference)
- Men: ≥102 cm (40 inches) 1
- Women: ≥88 cm (35 inches) 1
- Important caveat: The International Diabetes Federation initially proposed lower, ethnic-specific thresholds (94 cm for Europid men, 80 cm for Europid women), but the harmonized 2009 consensus statement allows use of population-specific cut points while maintaining the higher values as standard 1
2. Elevated Triglycerides
- Threshold: ≥1.7 mmol/L (150 mg/dL) 1
- Alternatively, patient is on drug treatment for elevated triglycerides 1
3. Reduced HDL Cholesterol
- Men: <1.03 mmol/L (<40 mg/dL) 1
- Women: <1.29 mmol/L (<50 mg/dL) 1
- Alternatively, patient is on drug treatment for reduced HDL 1
4. Elevated Blood Pressure
- Threshold: Systolic BP ≥130 mmHg and/or diastolic BP ≥85 mmHg 1
- Alternatively, patient is on antihypertensive drug treatment with a history of hypertension 1
5. Elevated Fasting Glucose
- Threshold: ≥5.6 mmol/L (100 mg/dL) 1
- Alternatively, patient has previously diagnosed type 2 diabetes 1
- Note: The 2009 harmonized criteria adopted the lower cut point of 100 mg/dL (previously 110 mg/dL in some definitions) 1
Key Clinical Points
No Single Component is Mandatory
- Unlike earlier International Diabetes Federation criteria that required central obesity as obligatory, the harmonized 2009 consensus states that any 3 of the 5 components qualify for diagnosis 1
- This approach acknowledges that metabolic risk exists across different phenotypic presentations 1
Waist Circumference as Screening Tool
- While not mandatory for diagnosis, waist measurement serves as a useful preliminary screening tool to identify at-risk patients 1
- Ethnic-specific cut points may be applied based on population characteristics, though standardized values remain the default 1
Clinical Significance
- Patients with metabolic syndrome have 2-fold increased risk of cardiovascular disease over 5-10 years 1, 2
- The syndrome confers a 5-fold increased risk for type 2 diabetes mellitus 1, 2
- Risk increases proportionally with the number of components present 2
Common Pitfalls to Avoid
Do not require insulin resistance testing for diagnosis. The harmonized criteria specifically eliminated this requirement from earlier WHO definitions, making diagnosis based purely on clinical measurements 1
Do not exclude patients with existing diabetes or cardiovascular disease. These patients can still be diagnosed with metabolic syndrome, and the number of components present contributes to disease progression 1
Do not use metabolic syndrome as an absolute risk calculator. It does not incorporate age, sex, smoking status, or LDL cholesterol—use formal cardiovascular risk calculators (e.g., Framingham Score) for absolute risk assessment 1