How to best define the metabolic syndrome

Figures & data

Figure 1. The two most common conceptual frameworks used to describe the metabolic syndrome. InA, there is a presumed underlying feature which is related to and causes the other variables. In B, the metabolic syndrome is represented by a set of variables which cluster with each other and no variable is known to be at the aetiological core.

Table I. Current definitions of the metabolic syndrome.

WHO 1999	EGIR 1999	ATPIII 2001	IDF 2005
Diabetes or impaired glucose tolerance or insulin resistance*	Insulin resistance^† or hyperinsulinaemia (only non‐diabetic subjects)		Central obesity
			Waist circumference (ethnicity specific)^‡
Plus two or more of the following:	Plus two or more of the following:	Three or more of the following:	Plus any two of the following:
1. Obesity: BMI>30 kg/m^2 or waist‐hip ratio>0.9 (M)>0.85 (F)	1. Central obesity: waist circumference⩾94 cm (M), ⩾80 cm (F)	1. Central obesity: waist circumference>102 cm (M), >88 cm (F)	1. Raised triglycerides⩾150 mg/dL (1.7 mmol/L) or specific treatment for this abnormality.
2. Dyslipidaemia: triglycerides⩾150 mg/dL (1.7 mmol/L) or HDL‐C<35 mg/dL (0.9 mmol/L) (M)<39 mg/dL (1.0 mmol/L) (F)	2. Dyslipidaemia: triglycerides>177 mg/dL (2.0 mmol/L) or HDL‐C<40 mg/dL (1.0 mmol/L)	2. Hypertriglyceridaemia: triglycerides⩾150 mg/dL (1.7 mmol/L)	2. Reduced HDL‐C<40 mg/dL (1.03 mmol/L) (M)<50 mg/dL (1.29 mmol/L) (F) or specific treatment for this abnormality
3. Hypertension: blood pressure⩾140/90 mmHg or medication	3. Hypertension: blood pressure⩾140/90 mmHg or medication	3. Low HDL‐C:<40 mg/dL (1.03 mmol/L) (M), <50 mg/dL (1.29 mmol/L) (F)	3. Hypertension: blood pressure⩾ 130/85 mmHg or medication.
4. Microalbuminuria: albumin excretion⩾20 μg/min or albumin:creatinine ratio⩾30 mg/g	4. Fasting plasma glucose⩾110 mg/dL (6.1 mmol/L)	4. Hypertension: blood pressure⩾130/85 mmHg or medication	4. Fasting plasma glucose⩾100 mg/dL (5.6 mmol/L) or previously diagnosed type 2 diabetes^§
		5. Fasting plasma glucose⩾110 mg/dL (6.1 mmol/L)

*Defined under hyperinsulinaemic euglycaemic conditions, glucose uptake below lowest quartile for background population. ^†Defined as the top quartile of fasting insulin in the non‐diabetic population. ^‡For guidelines on how to accurately measure waist circumference see table II. If BMI is>30 kg/m² then central obesity can be assumed, and waist circumference does not need to be measured. ^§In clinical practice, IGT is also acceptable, but all reports of the prevalence of the metabolic syndrome should use only the fasting plasma glucose and presence of previously diagnosed diabetes to assess this criteria. If fasting plasma glucose is above 5.6 mmol/L, OGTT is strongly recommended but is not necessary to define the presence of the syndrome.

WHO = World Health Organization; EGIR = the European Group for the Study of Insulin Resistance; the American college of Endocrinology Task Force on the Insulin Resistance Syndrome; ATPIII = National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III); IDF = International Diabetes Association; F = female; M = male.

Table II. ‘Identifying abnormalities’ according to the American College of Endocrinology position statement on the Insulin Resistance Syndrome.

Identifying abnormality	Cut point
1. Triglycerides:	>150 mg/dL (1.7 mmol/L)
2. HDL Cholesterol:
Men	<40 mg/dL (1.03 mmol/L)
Women	<50 mg/dL (1.29 mmol/L)
3. Blood Pressure:	>130/85 mmHg
4. Glucose:
Fasting	110–125 mg/dL (6.1 mmol/L)
2 hour post glucose challenge	140–200 mg/dL ( 7.8–11.1 mmol/L )

Table III. Country‐/ethnic‐specific values for waist circumference.

Country/ethnic group*		Waist circumference^† (as measure of central obesity)
Europids^‡	Male	⩾94 cm
	Female	⩾80 cm
South Asians^§	Male	⩾90 cm
	Female	⩾80 cm
Chinese	Male	⩾90 cm
	Female	⩾80 cm
Japanese	Male	⩾85 cm
	Female	⩾90 cm
Ethnic South and Central Americans	Use South Asian recommendations until more specific data are available
Sub Saharan Africans and Eastern Mediterranean and Middle East (Arab) populations	Use European data until more specific data are available

*Ethnicity should be the basis for classification, not the country of residence. ^†In the USA the ATP III values (102 cm male; 88 cm female) are likely to continue to be used for clinical purposes. ^‡In future epidemiological studies of populations of Europid origin, prevalence should be given using both European and North American cut points to allow better comparisons. ^§Based on a Chinese, Malay and Asian‐Indian population.