The metabolic syndrome as predictor of type 2 diabetes: the San Antonio heart study.
OBJECTIVE
The oral glucose tolerance test identifies high-risk subjects for diabetes, but it is costly and inconvenient. To find better predictors of type 2 diabetes, we evaluated two different definitions of the metabolic syndrome because insulin resistance, which is commonly associated with this clustering of metabolic factors, frequently precedes the onset of type 2 diabetes.


METHODS
We compared the ability of the National Cholesterol Education Program (NCEP) definition, a modified version of the 1999 World Health Organization (WHO) definition that excludes the 2-h glucose requirement, and impaired glucose tolerance (IGT) to predict incident type 2 diabetes. In the San Antonio Heart Study, 1734 participants completed a 7- to 8-year follow-up examination.


RESULTS
IGT and the NCEP definition had higher sensitivity than the modified WHO definition (51.9, 52.8, and 42.8%, respectively). IGT had a higher positive predictive value than the NCEP and modified WHO definitions (43.0, 30.8, and 30.4%, respectively). The combination of the IGT and NCEP definitions increased the sensitivity to 70.8% with an acceptable positive predictive value of 29.7%. Risk for incidence of type 2 diabetes using the NCEP definition was independent of other risk factors, including IGT and fasting insulin (odds ratio 3.30, 95% CI 2.27-4.80). The NCEP definition performed better with fasting glucose >or=5.4 mmol/l (sensitivity 62.0% and positive predictive value 30.9%).


CONCLUSIONS
The metabolic syndrome predicts diabetes independently of other factors. However, the NCEP definition performs better than the modified 1999 WHO definition. Lowering the fasting glucose cutoff to 5.4 mmol/l improves the prediction of diabetes by the metabolic syndrome.
Lorenzo
Carlos
C
Division of Clinical Epidemiology, University of Texas Health Science Center, San Antonio, Texas 78284-7873, USA. lorenzo@uthsca.edu
Okoloise
Mayor
M
Williams
Ken
K
Stern
Michael P
MP
Haffner
Steven M
SM
D000328:Adult; D001786:Blood Glucose; D015992:Body Mass Index; D003920:Diabetes Mellitus / Q000175:diagnosis / Q000453:epidemiology; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis* / Q000453:epidemiology*; D005215:Fasting; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D015994:Incidence; D007328:Insulin / Q000097:blood; D008297:Male; D024821:Metabolic Syndrome / Q000175:diagnosis* / Q000453:epidemiology*; D008875:Middle Aged; D009765:Obesity; D011237:Predictive Value of Tests; D012307:Risk Factors; D012680:Sensitivity and Specificity
D001786:Blood Glucose; D007328:Insulin