In an investigation between leptin levels and incident frailty in 1,573 individuals from the Seniors-ENRICA cohort, aged ≥ 60 years and without T2DM [67], those with leptin levels in the highest tertile had a significantly increased risk of frailty (odds ratio [OR]: 2.12; 95% confidence interval [CI]: 1.47–3.06; p-trend < 0.001). This evidence concerns the gene LEP and type 2 diabetes mellitus.