This gene encodes insulin, a peptide hormone that plays a vital role in the regulation of carbohydrate and lipid metabolism. The encoded precursor protein undergoes proteolytic cleavage to produce a disulfide-linked heterodimeric functional protein that is stored in secretory granules. An increase in blood glucose levels, among others, induces the release of insulin from the secretory granules. Mice deficient in the functional hormone encoded by this gene develop diabetes mellitus. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Aug 2015]