LEP and type 2 diabetes mellitus: However, among individuals with T2D, serum 25(OH)D concentrations were marginally associated with IL-6 (R2 = 0.109, B = 0.076, P = 0.085) in HA with T2D, and there was a trend toward significance in the association with log leptin (R2 = 0.393, B = − 0.006, P = 0.075) in AA with T2D in regression analysis.