1412-P: Change in Insulin Secretion Along with Aging in a General Japanese Population

Objective: Although increase in type 2 diabetes (DM) along with aging is well documented, change in insulin secretion along with aging and factors related to its change in general, nondiabetic, population has not been well examined so far. Therefore, we evaluated the relationships between insulin secretion and age, or aging, in a general population.

Methods: 1. cross sectional study: Among participants of the population-based Iwaki study of Japanese people held in 2014-2017, those without diabetes were enrolled (gender (M/F): 536/882; age: 53.0±16.0) 2. longitudinal study: Among participants described above, those attended the study consecutively in 2014 and 2017 were enrolled (gender (M/F): 257/401; age: 53.7±14.1). Insulin secretion was evaluated using homeostasis model assessment (HOMA-β).

Results: 1: Univariate regression analyses revealed that the relationship between HOMA-β and age appeared to be non-linear but L-shaped, with an inflection point at about 55 and 50 years for men and women, respectively. Under the ages, HOMA-β are correlated with age (β= -0.32, p<0.01, and β=-0.16, p<0.01, for men and women, respectively), while above the age, such correlation was not observed (p=0.06 and 0.42, respectively).2: Analyses to evaluate factors associated with such decreases in HOMA-β in the 3-year duration showed no significant factor for men but HDL-c (β= -0.30, p<0.01), FIB-4 index representing degree of fibrotic change of liver (β=0.25, p=0.01) and for women after adjustment for multiple factors such as BMI, serum lipid parameters, and, so on.

Conclusions: Insulin secretion seems to decrease along with aging till middle age, but after the age, it dose not decrease or stays similar throughout in a general Japanese population, indicating that aging per se may not be a major determinant for impaired insulin secretion in a general, or physiological condition. Further, factors related to abnormal liver function can be markers to predict decrease in insulin secretion, at least, in women.