Serum 25-hydroxyvitamin D and adipose tissue vitamin D receptor gene expression: Relationship with obesity and type 2 diabetes

Abstract

Context: The relationship between 25-hydroxyvitamin D [25(OH)D] and obesity and type 2 diabetes is not completely understood. Vitamin D receptor (VDR) expression in adipose tissue (AT) is related to obesity and might be regulated by 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. Objective: To analyze serum 25(OH)D and VDR gene expression in AT according to body mass index (BMI) and glycemic status and the effect of 1,25(OH)2D3 on AT according to BMI. Design and Patients: Two cohorts were studied: 1)118 subjects classified according to their BMI (lean, overweight, obese, or morbidly obese [MO]) and their glycemic status (normoglycemic [NG] and prediabeticand diabetic [P&D]); and 2) 30 obese subjects (BMI > 30 kg/m2) classified as NG and P&D. VDR gene expression was analyzed during preadipocyte differentiation and in vitro stimulation with 1,25(OH)2D3 of AT explants from donors with different BMI values. Setting: University Hospital. Main Outcome Measures: Serum 25(OH)D, parathyroid hormone (PTH), and AT VDR gene expression. Results: 25(OH)D levels were lower in P&D than NG subjects, significantly so in the lean and MO groups (P