<h4>Aim</h4>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).<h4>Patients and methods</h4>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. This evidence concerns the gene INS and diabetes mellitus.