Our findings challenge some views about the biological roles of vitamin D. Although the direct mechanisms are unclear, previous findings have suggested roles for vitamin D in type 2 diabetes.1, 3 For example, results of rodent experiments showed that 1,25-dihydroxyvitamin D (1,25[OH]2D), an active form of vitamin D, regulates calcium-dependent signalling, modulates insulin secretion in pancreatic β cells, and reduces lipotoxicity of free fatty acids.3 The gene discussed is INS; the disease is type 2 diabetes mellitus.