Aims: To assess the cardiovascular (CVD) risk factor profile in individuals with diabetes and impaired glucose tolerance (IGT) identified by a one-step (fasting plasma glucose (FPG)) or a two-step strategy (including an oral glucose tolerance test (OGTT) in subjects with impaired fasting glucose (IFG)) as recommended by the World Health Organization (WHO).
Methods: Twelve population-based studies in six countries (17 512 subjects, age 30-89 years, without known diabetes, with OGTT (fasting and 2-h plasma glucose (2-h PG))). Age, gender, and centre-adjusted means of CVD risk factors were compared according to the level of glucose intolerance.
Results: Diabetes was found in 1270 individuals and IFG or IGT in 3158. In the diabetic group 55.1% had a FPG > or = 7.0 mmol/l (range between countries 36.2-67.0%), 20.5% were identified through the stepwise strategy (range 0-32%), while 24.4% would remain undiagnosed (FPG < 6.1 mmol/l) (range 9.0-40.0%). The two-step strategy identified 60-91% of all newly diagnosed diabetic subjects with 5-12% of the population requiring an OGTT. Mean body mass index (BMI), blood pressure, and total cholesterol did not differ between diabetic individuals diagnosed by FPG or OGTT. The step-wise strategy identified < 50% of the subjects with impaired glucose regulation, and the cardiovascular risk profile (BMI, blood pressure, and cholesterol) did not differ between those identified and those not identified in the screening process.
Conclusions: Applying an OGTT in subjects with IFG will fail to detect every fourth diabetic individual and every second individual with impaired glucose regulation. Individuals not diagnosed had a cardiovascular risk profile identical to those identified in the diagnostic process. Lower thresholds for an OGTT may be necessary in Asian populations.