Purpose: Testing 1-h glucose (1HG) concentration during oral glucose tolerance test is cost-effective to identify individuals at risk of incident type 2 diabetes. Aim of the study was to define 1HG cutoffs diagnostic of incident impaired glucose tolerance (IGT) in youths with obesity, and to evaluate prevalence and association of cutoffs identified in the cohort and from the literature (133 and 155 mg/dl) to cardiovascular disease (CVD) in a population of youths with obesity.
Methods: This is a longitudinal study of 154 youths to identify 1HG cutoffs, and cross-sectional study of 2295 youths to estimate prevalence of high 1HG and association to CVD. Receiver-operating characteristic curves (ROC) were used to establish 1HG cutoffs, and univariate regression analyses to test association of 1HG to blood pressure, lipids and aminotransferases.
Results: ROC analysis identified the 1HG cutoff of 159 mg/dl as having diagnostic accuracy of IGT with area under the ROC 0.82 (95% CI 0.66-0.98), sensitivity 0.86% and specificity 0.79%. In the cross-sectional population, prevalence of high 1HG was 36% and 15% for 133 and 155 mg/dl cutoffs, respectively, and 17% for the 159 mg/dl value. All the examined cutoffs were significantly associated with worse lipid profile, liver function test, reduced insulin sensitivity, secretion and disposition index.
Conclusion: High 1HG is marker of persistent IGT and increased risk of metabolic abnormalities in youths. The 155 mg/dl cutoff is a convenient estimate in young people but longitudinal studies with retinopathy and overt diabetes as end points are advised to verify the 1HG cutoff with the best diagnostic accuracy.
Keywords: 1-h glucose; Insulin secretion; Insulin sensitivity; Oral glucose tolerance test; Prediabetes.
© 2023. The Author(s), under exclusive licence to Italian Society of Endocrinology (SIE).