Aims: To determine factors predicting isolated postchallenge hyperglycaemia (IPH) defined as fasting plasma glucose (FPG) < 7.0 mmol/l and 2-h plasma glucose (2-hPG) >or= 11.1 mmol/l after an oral glucose tolerance test (OGTT) and factors influencing the value of 2-hPG in a population-based study.
Materials and methods: From 15,005 participants in the Tehran Lipid and Glucose Study (TLGS), we analysed the results of OGTTs in 5386 individuals (2909 women and 2437 men) aged >or= 20 years, free of known diabetes and any other disorders influencing glucose metabolism. Logistic and multiple linear regression models were developed to predict IPH and the 2-hPG, respectively.
Results: The overall prevalence of non-diabetic subjects, IPH and undiagnosed Type 2 diabetes mellitus (FPG >or= 7.0 mmol/l) were 94.5% (n = 5088), 2.5% (n = 133) and 3.1% (n = 165), respectively. Of subjects with IPH, 29.3% (n = 39) had FPG levels < 5.6 mmol/l. Factors associated with IPH were FPG (mmol/l) [odds ratio (OR) 11.05, 95% confidence interval (CI) 7.9, 15.4], age >or= 40 years (OR 2.0, 95% CI 1.3, 3.2), abnormal waist circumference (OR 2.1, 95% CI 1.4, 3.1) and serum triglycerides >or= 1.7 mmol/l (OR 2.0, 95% CI 1.3, 3.1). In the multiple linear regression model, six explanatory factors (FPG, age, female sex, triglycerides, systolic blood pressure, waist circumference) were positively related to 2-hPG.
Conclusions: The model could predict 47.7% of total variance of 2-hPG. Based on our results in this Iranian population, OGTT can be recommended in subjects with FPG < 7.0 mmol/l in the presence of abnormal waist circumference and triglycerides, age >or= 40 years and in particular when FPG is close to 7.0 mmol/l.