Sex differences in insulin resistance and basal insulin secretion among elderly men and women without a history of diabetes: a comparative study between obese and non-obese groups

Aim The aim of this study was to examine sex differences in insulin resistance and basal insulin secretion among elderly individuals without a history of diabetes, comparing obese and non-obese groups in early elderly (aged 65–74 years) and late elderly (aged 75–89 years). Patients and methods A total of 478 individuals (258 men and 220 women) who underwent comprehensive medical checkups at Tsunan Municipal Hospital between 2008 and 2014 were included. We investigated whether there were interactive effects between age and Body Mass Index (BMI) on homeostasis model assessment of insulin resistance (HOMA-IR) values and homeostasis model assessment of beta cell function (HOMA-β) values, and examined their associations with each factor using analysis of variance (ANOVA) and multivariate analysis. Results In elderly men, elevated BMI was significantly associated with higher HOMA-IR values, and HOMA-β values were also significantly higher in the obese group than in the non-obese group. In contrast, among elderly women, HOMA-β values in the obese group were comparable to those in the non-obese group regardless of early and late elderly. Conclusions In elderly men, insulin resistance associated with obesity was firmly present regardless of age, whereas, in elderly women, there is no difference in basal insulin secretion between the obese and non-obese groups irrespective of age.