Prolonged plasma glucose elevation on oral glucose tolerance test in young healthy Japanese individuals

AIMS: This study aims to assess insulin secretion and resistance through oral glucose tolerance test (OGTT) among young Japanese individuals. SUBJECTS AND METHODS: We enrolled 595 young healthy Japanese individuals aged 22‐29 years. They underwent an OGTT, and their results were divided into 4 groups (I‐IV), according to the time at which their plasma glucose concentration declined below the fasting glucose concentration (30, 60 or 120 minutes or never as groups I, II, III and IV, respectively). RESULTS: We classified 575 normal glucose‐tolerant subjects into 4 groups (I‐IV) with I: 28 (4.9%), II: 120 (20.9%), III: 143 (24.9%) and IV: 284 (49.4%) individuals. The Matsuda, insulinogenic and disposition indices were decreased from groups I to IV. ROC curves of disposition index reflecting the composition of insulin secretion and sensitivity classified the prolonged glucose elevation group (group III + IV) from the rapid glucose lowering group (group II; AUC = 0.847). CONCLUSIONS: Even in a young and healthy Japanese individual within the physiological range of glycaemic control, there is a sequential decrease in insulin sensitivity and secretion.