Fine-tuning of prediction of isolated impaired glucose tolerance: A quantitative clinical prediction model

In this cross-sectional study, we evaluated results of oral glucose tolerance test (OGTT) from 4742 women and 3470 men, participated in the Tehran Lipid and Glucose Study, aged ≥20 years and without diabetes, to determine the diagnostic value of subjects' clinical traits with isolated impaired glucose tolerance (isolated-IGT) defined as fasting plasma glucose (FPG) <5.6 mmol/L and 2-h plasma glucose between 7.8 and 11.1 mmol/L. The overall prevalence of IGT was 13.6% (n = 1120); of these subjects, 59.6% (n = 668) had isolated-IGT. The adjusted odds ratios for having isolated-IGT among 7012 subjects with FPG <5.6 mmol/L were significant for age ≥40 years (2.5), hypertension (1.9), abnormal waist circumference (1.9), obesity (1.5), and family history of diabetes (1.3). Adding the lipid profiles to the clinical model increased the area under the ROC curve only slightly (73.2% vs. 72.1%, respectively; P = 0.002). In summary, this study showed that in adults with FPG <5.6 mmol/L, older age, family history of diabetes, abnormal waist circumference and obesity, and hypertension were significantly associated with a higher likelihood of isolated-IGT; OGTT could hence be recommended in subjects who have most of these characteristics to find Isolated-IGT, especially if the findings are supported by appropriately designed clinical trials.