title: Vitamin D deficiency: a new risk factor for type 2 diabetes?.
abstract: Recent compelling evidence suggests a role of vitamin D deficiency in the pathogenesis of insulin resistance and insulin secretion derangements, with a consequent possible interference with type 2 diabetes mellitus. The mechanism of this link is incompletely understood. In fact, vitamin D deficiency is usually detected in obesity in which insulin resistance is also a common finding. The coexistence of insulin resistance and vitamin D deficiency has generated several hypotheses. Some cross-sectional and prospective studies have suggested that vitamin D deficiency may play a role in worsening insulin resistance; others have identified obesity as a risk factor predisposing individuals to exhibit both vitamin D deficiency and insulin resistance. The available data from intervention studies are largely confounded, and inadequate considerations of seasonal effects on 25(OH)D concentrations are also a common design flaw in many studies. On the contrary, there is strong evidence that obesity might cause both vitamin D deficiency and insulin resistance, leaving open the possibility that vitamin D and diabetes are not related at all. Although it might seem premature to draw firm conclusions on the role of vitamin D supplementation in reducing insulin resistance and preventing type 2 diabetes, this manuscript will review the circumstances leading to vitamin D deficiency and how such a deficiency can eventually independently affect insulin sensitivity.
authors.affiliation: Endocrinologia, Università Cattolica del Sacro Cuore, Roma, Italia. teresa.mezza@gmail.com
authors.forename: T
authors.initials: T
authors.lastname: Mezza
authors.forename: G
authors.initials: G
authors.lastname: Muscogiuri
authors.forename: G P
authors.initials: GP
authors.lastname: Sorice
authors.forename: A
authors.initials: A
authors.lastname: Prioletta
authors.forename: E
authors.initials: E
authors.lastname: Salomone
authors.forename: A
authors.initials: A
authors.lastname: Pontecorvi
authors.forename: A
authors.initials: A
authors.lastname: Giaccari
mesh_terms: D003924:Diabetes Mellitus, Type 2 / Q000209:etiology / Q000503:physiopathology*; D006706:Homeostasis; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance; D000078790:Insulin Secretion; D009765:Obesity / Q000209:etiology / Q000503:physiopathology; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors; D014807:Vitamin D / Q000008:administration & dosage; D014808:Vitamin D Deficiency / Q000150:complications / Q000503:physiopathology*; D014815:Vitamins / Q000008:administration & dosage
chemical_list: D007328:Insulin; D014815:Vitamins; D014807:Vitamin D