老年者耐糖能異常での膵β細胞機能とインスリン感受性

Abstract

Glucose tolerance has been shown to decline with age, but the mechanisms of this phenomenon are not yet completely defined. We assessed the pancreatic beta-cell function and the insulin sensitivity in elderly Japanese subjects using fasting and 75g- oral glucose tolerance test measurements of glucose and insulin. One hundred eighty- two subjects were classified into three categories according to the status of glucose intolerance: normal glucose tolerance (NGT, n=82), impaired glucose tolerance (IGT, n= 81), and diabetes mellitus (DM, n=19). Insulinogenic index and 1st-phase insulin secretion index declined with worsening glucose tolerance. The 2nd-phase insulin secretion index was significantly lower in DM than in IGT. Homeostasis model assessment of insulin resistance (HOMA-IR) increased with worsening glucose tolerance, whereas the insulin sensitivity index (ISI) and the metabolic clearance rate of glucose (MCR) decreased with worsening glucose tolerance. We concluded that the pancreatic beta-cell dysfunction as well as impaired insulin sensitivity contribute to glucose intolerance in elderly Japanese subjects.