In contrast, the elegant study of Nwosu and Maranda showed a significant reduction of HbA1c after 3 months of ergocalciferol or cholecalciferol supplementation in children and adolescents with T2DM but not in subjects with T1DM [36] and the IMDIAB XIII study did not found differences in dose of insulin, HbA1c and C-peptide at 6, 12, 24 months of treatment with calcitriol (0.25 mcg/day) vs placebo in adolescents and young adults with newly diagnosed T1DM and high baseline levels of C-peptide [42]. The gene discussed is INS; the disease is type 1 diabetes mellitus.