Diagnostic performance of 2 h postprandial capillary and venous glucose as a screening test for abnormal glucose tolerance

AimsTo evaluate the diagnostic performance of postprandial venous and capillary glucose to screen for abnormal glucose tolerance in primary care setting.MethodsBoth post-breakfast venous plasma and capillary blood glucose were taken simultaneously from a consecutive sample of volunteer civil service workers in Khon Kaen, Thailand between June and December 2009. The 75-g oral glucose tolerance test was performed within 3 days of the baseline visit. Both postprandial capillary and venous glucose were assessed for sensitivity, specificity, area under the receiver operating characteristic (ROC) curve and likelihood ratio using the oral glucose tolerance test (OGTT) results for the diagnosis of abnormal glucose tolerance as a gold standard.Results1102 volunteers participated, of whom 874 (79.3%) completed the full study protocol. Five-hundred and four (57.8%) of 874 participants were female. The mean age was 39.9 years (SD = 12.16) and the mean BMI was 24.3 kg/m2 (SD = 6.86). The sensitivity and specificity at the optimal cut-off point for venous glucose were 68.28% (95% CI 60.04–75.75) and 67.90% (95% CI 64.38–71.28), respectively. The sensitivity and specificity at the optimal cut-off point for capillary glucose were 63.45% (95% CI 55.05–71.28) and 64.06% (95% CI 60.46–67.55), respectively. The area under the ROC curve was 0.73 (95% CI 0.68–0.78) for venous glucose and 0.69 (95% CI 0.64–0.74) for capillary glucose. The subgroup analysis involving individuals with waist circumference > 90 cm improved the area under the curve (AUC) to 0.76 (95% CI 0.68–0.83).ConclusionsPostprandial blood glucose testing had a moderate discriminating characteristic for the diagnosis of abnormal glucose tolerance. Careful consideration is needed when using it to screen for this condition in general population.