Hypovitaminosis D is commonly observed in many countries; it is known to be closely associated with increased insulin resistance, impaired insulin secretion, and poorly controlled glucose homeostasis, and thus is correlated with the risk of metabolic diseases, such as type 2 diabetes mellitus (T2DM) and non-alcoholic fatty liver disease (NAFLD). Here, INS is linked to metabolic dysfunction-associated steatotic liver disease.