1216-P: Effects of Aging after Age 65 on Glucose Tolerance, Insulin Sensitivity, and ß-Cell Function in Japanese—The Bunkyo Health Study

The number of new-onset diabetes cases in elderly adults is on the rise, and it is particularly prominent in Japan in which the ageing rate is the highest in the world. With ageing, both insulin sensitivity and insulin secretion deteriorate, however, it remains unclear whether these factors are further exacerbated with ageing in persons older than 65 years. The purpose of this study was to determine age-related changes in glucose tolerance and its related factors in Japanese elderly adults after age 65. Here, we studied 1438 old adults who were not taking oral hypoglycemic agents and were not diagnosed with diabetes. All subjects were assessed for glucose tolerance, insulin sensitivity (Matsuda index and Adipo-IR (fasting insulin x fasting free fatty acid (FFA)) and β-cell function (insulinogenic index) by 75g oral glucose tolerance test (OGTT). We divided participants according to age (65-69 years (n=465), 70-74 years (n=422), 75-79 years (n=326), and 80-84 years (n=225)) and compared clinical characteristics by ANOVA and post-hoc analysis. The mean BMI of all subjects was normal range (22.7±3.0kg/m2). The prevalence of newly diagnosed diabetes increased with age (7.5%, 11.1%, 12.0%, 18.7%, respectively). Fasting plasma glucose, serum insulin levels and insulinogenic index were comparable among the groups; however, area under the curve (AUC)-glucose and AUC-insulin during the 75g OGTT were significantly higher and Matsuda index and disposition index were significantly lower in the 70-74, 75-79 and 80-84 years groups than in the 65-69 years group. Similarly, percent body fat, fasting FFA and Adipo-IR were significantly higher in the 75-79 and 80-84 years groups than in the 65-69 years group. In conclusion, ageing in Japanese after age 65 is associated with exacerbation of body fat accumulation, adipose tissue and systemic IR, which, combined with decreased β-cell compensatory function, leads to worsening glucose tolerance.