Vitamin D is a fat-soluble vitamin, and it is involved in a variety of physiological processes such as calcium homeostasis, immune functioning and regulation of cell proliferation. A recent study has also demonstrated its possible involvement in insulin sensitivity, a key biomarker involved in glucose metabolism and T2DM development. The biologically active vitamin D metabolite, 1,25-dihydroxyvitamin D (1,25(OH)2D), acts on VDRs in various tissues including pancreatic beta cells and has an effect on insulin secretion and sensitivity. Given the widespread vitamin D deficiency in T2DM, the association between vitamin D supplementation and insulin sensitivity has been inconsistent across studies. Observational studies generally have found a direct association between them, but randomized controlled trials (RCTs) are more modest. This review critically analyzes mechanisms by which vitamin D may influence metabolic health, such as through inflammation, oxidative stress and calcium homeostasis. It also highlights public health interventions, including food fortification and selective supplementation programs to address vitamin D deficiency and enhance metabolic status.