Objective: Aging is one of the risks for abnormal glucose tolerance or diabetes. Although association between age and, insulin secretion and resistance has been reported in various cross sectional studies, few studies evaluated changes of insulin resistance and secretion along with aging.
Research Design and Methods: Among participants of the population-based Iwaki study of Japanese, those participated consecutively from 2014 to 2017 and were nondiabetic were included in this study (Men/Women: 200/294; Age: 21-90 (54.2 ± 13.5)). The effects of aging on homeostasis model assessment indices for insulin resistance (HOMA-R) and β-cell function (HOMA-β) were examined.
Results: During the 3-year periods, HOMA-R significantly increased (p<0.0001), while HOMA-β significantly decreased (p<0.0001). Repeatedly measures ANOVA with adjustments for possible confounding and/or intermediating factors showed that the increase in HOMA-R became insignificant after adjustment with factors related to adiposity such as BMI and leptin (p=0.564), while the decrease in HOMA-β stayed significant even after such adjustments (p=0.046). Despite the facts, stepwise multiple regression analysis showed significant association of leptin not only with increases in HOMA-R (p=0.022) but also with decreases in HOMA-β (p =0.003).
Conclusion: Insulin resistance increases along with aging probably due to a simultaneous adiposity, while insulin secretion decreases along with aging at least in part independently of such adiposity. However, the association between leptin and decreases in HOMA-β may suggest that adiposity of β-cells may be in part blamed for the decreases. Further, leptin may be a marker to predict those at risk of decreasing insulin secretion. We are now examining such association in details in consideration with blood metabolites and amino acids levels.
T. Fujita: None. M. Daimon: None. H. Murakami: None. S. Mizushiri: None. Y. Matsuhashi: None. S. Osonoi: None. M. Murabayashi: None. K. Takahashi: None. Y. Nishiya: None.