INS and prediabetes syndrome: In a recent placebo-controlled study by Gagnon et al., vitamin D3 upplementation for six months with a dose aimed at increasing the serum 25(OH)D3 to ≥75 nmol/L (2000–6000 IU/d, 50–150 μg/d) improved insulin sensitivity in subjects with prediabetes, but not in subjects without prediabetes [7].