LEP and diabetic kidney disease: IL-6, IL-8, leptin, and adiponectin concentrations increased progressively from NDC to C-T2D, NC-T2D, and DKD (IL-6, p ≤ 0.001; IL-8, p < 0.001; leptin, p < 0.001; adiponectin, p ≤ 0.006).