Who should return for an oral glucose tolerance test? A proposed clinical pathway based on retrospective analysis of 332 children

Abstract

Fasting plasma glucose or oral glucose tolerance test (OGTT) is the traditional diagnostic tool for type 2 diabetes (T2DM). However, fasting is required and implementation in all overweight/obese subjects is not practical. This study aimed to formulate a clinical pathway to stratify subjects according to their risk of abnormal OGTT. This retrospective study included patients with overweight or obesity who had undergone OGTT in a tertiary paediatric unit from 2012 to 2018. The optimal haemoglobin A1c (HbA1c) cutoff that predicts abnormal OGTT was evaluated. Other non-fasting parameters, in combination with this HbA1c cutoff, were also explored as predictors of abnormal OGTT. Three hundred and thirty-two patients (boys: 54.2%, Chinese: 97.3%) were included for analysis, of which, 272 (81.9%) patients had normal OGTT while 60 (18.0%) patients had abnormal OGTT (prediabetes or T2DM). Optimal HbA1c predicting abnormal OGTT was 5.5% (AUC 0.71; sensitivity of 66.7% and specificity of 71%). When HbA1c≥5.5% was combined with positive family history and abnormal alanine transaminase (ALT) level, the positive predictive value for abnormal OGTT was increased from 33.6 to 61.6%. HbA1c, family history of T2DM and ALT level could be used to derive a clinical pathway to stratify children who have high risk of abnormal OGTT.