Serum 25(OH)D concentrations were correlated negatively with BMI, log HOMA-IR, TC, LDL-c, and log leptin, but positively with HOMA2-IS, and adiponectin in AA without T2D, and positively with HOMA2-IS, but negatively with log leptin in AA with T2D. The gene discussed is ADIPOQ; the disease is type 2 diabetes mellitus.