Endocrinology, Catholic University, Rome, Italy.
Obesity (Silver Spring). 2010 Oct;18(10):1906-10. doi: 10.1038/oby.2010.11. Epub 2010 Feb 11.
The prevalence of hypovitaminosis D is high among obese subjects. Further, low 25-hydroxyvitamin D (25(OH)D) concentration has been postulated to be a risk factor for type 2 diabetes, although its relation with insulin-sensitivity is not well investigated. Thus, we aimed to investigate the relationship between 25(OH)D concentration and insulin-sensitivity, using the glucose clamp technique. In total, 39 subjects with no known history of diabetes mellitus were recruited. The association of 25(OH)D concentration with insulin-sensitivity was evaluated by hyperinsulinemic euglycemic clamp. Subjects with low 25(OH)D (<50 nmol/l) had higher BMI (P = 0.048), parathyroid hormone (PTH) (P = 0.040), total cholesterol (P = 0.012), low-density lipoprotein (LDL) cholesterol (P = 0.044), triglycerides (P = 0.048), and lower insulin-sensitivity as evaluated by clamp study (P = 0.047). There was significant correlation between 25(OH)D and BMI (r = -0.58; P = 0.01), PTH (r = -0.44; P < 0.01), insulin-sensitivity (r = 0.43; P < 0.01), total (r = -0.34; P = 0.030) and LDL (r = -0.40; P = 0.023) (but not high-density lipoprotein (HDL)) cholesterol, and triglycerides (r = 0.45; P = 0.01). Multivariate analysis using 25(OH)D concentration, BMI, insulin-sensitivity, HDL cholesterol, LDL cholesterol, total cholesterol, and triglycerides, as the cofactors was performed. BMI was found to be the most powerful predictor of 25(OH)D concentration (r = -0.52; P < 0.01), whereas insulin-sensitivity was not significant. Our study suggested that there is no cause-effect relationship between vitamin D and insulin-sensitivity. In obesity, both low 25(OH)D concentration and insulin-resistance appear to be dependent on the increased body size.
肥胖人群中普遍存在维生素 D 缺乏症。此外，虽然低 25-羟维生素 D（25(OH)D）浓度被认为是 2 型糖尿病的危险因素，但它与胰岛素敏感性的关系尚未得到很好的研究。因此，我们使用葡萄糖钳夹技术旨在研究 25(OH)D 浓度与胰岛素敏感性之间的关系。共招募了 39 名无糖尿病病史的受试者。使用高胰岛素正葡萄糖钳夹技术评估 25(OH)D 浓度与胰岛素敏感性的相关性。25(OH)D 浓度低（<50nmol/l）的受试者体重指数（BMI）较高（P = 0.048）、甲状旁腺激素（PTH）较高（P = 0.040）、总胆固醇（P = 0.012）、低密度脂蛋白胆固醇（LDL-C）较高（P = 0.044）、甘油三酯（P = 0.048），并且通过钳夹研究评估的胰岛素敏感性较低（P = 0.047）。25(OH)D 与 BMI（r = -0.58；P = 0.01）、PTH（r = -0.44；P < 0.01）、胰岛素敏感性（r = 0.43；P < 0.01）、总胆固醇（r = -0.34；P = 0.030）和 LDL 胆固醇（r = -0.40；P = 0.023）（但高密度脂蛋白（HDL）胆固醇和甘油三酯（r = 0.45；P = 0.01）呈显著相关。使用 25(OH)D 浓度、BMI、胰岛素敏感性、HDL 胆固醇、LDL 胆固醇、总胆固醇和甘油三酯作为协变量进行多元分析。发现 BMI 是 25(OH)D 浓度的最强预测因子（r = -0.52；P < 0.01），而胰岛素敏感性则不显著。我们的研究表明，维生素 D 和胰岛素敏感性之间没有因果关系。在肥胖中，低 25(OH)D 浓度和胰岛素抵抗似乎都依赖于身体尺寸的增加。
