In a 2×2 factorial trial of vitamin D3 (2,000 IU/d) and calcium (800 mg/d) supplementation for 4 months in 92 mostly Caucasian individuals with prediabetes or early diabetes, Mitri et al. found no change in insulin sensitivity in all the treatment groups using the intravenous glucose tolerance test [10]. The gene discussed is INS; the disease is diabetes mellitus.