Department of Pediatrics, Division of General Academic Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
Diabetes Care. 2012 Mar;35(3):627-33. doi: 10.2337/dc11-1825. Epub 2012 Jan 11.
To examine the relationships between plasma 25-hydroxyvitamin D [25(OH)D] and in vivo insulin sensitivity and β-cell function relative to insulin sensitivity, disposition index (DI), in black and white youth.
Plasma 25(OH)D concentrations were analyzed in banked specimens in healthy youth aged 8 to 18 years who had existing data on hyperinsulinemic-euglycemic and hyperglycemic clamp to assess insulin sensitivity and secretion, and measurements of body composition, and abdominal visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT).
A total of 183 research volunteers (mean ± SD; age, 12.6 ± 2.2 years; 98 white, 98 male, 92 obese) were studied. Analysis of HbA(1c), fasting glucose and insulin, insulin sensitivity, and DI across quartiles of plasma 25(OH)D revealed no differences among whites. In blacks, the observed significance of higher insulin sensitivity and DI in the highest quartile of 25(OH)D disappeared after adjusting for any of the adiposity measures (BMI or fat mass or VAT or SAT). The difference in insulin sensitivity (9.4 ± 1.2 vs. 5.6 ± 0.5 mg/kg/min per μU/mL; P = 0.006) between 25(OH)D nondeficient (≥20 ng/mL) versus deficient (<20 ng/mL) black youth also was negated when adjusted for adiposity.
In healthy youth, plasma 25(OH)D concentrations bear no independent relationship to parameters of glucose homeostasis and in vivo insulin sensitivity and β-cell function relative to insulin sensitivity. It remains to be determined whether in youth with dysglycemia the relationships are different and whether vitamin D optimization enhances insulin sensitivity and β-cell function.
研究黑人及白人青少年群体中，血浆 25-羟维生素 D [25(OH)D]与体内胰岛素敏感性和β细胞功能的关系，及其与胰岛素敏感性、胰岛素分泌作用指数（DI）的关系。
在已有的对健康青少年进行高胰岛素-正葡萄糖钳夹和高血糖钳夹以评估胰岛素敏感性和分泌、身体成分以及腹部内脏脂肪组织（VAT）和皮下脂肪组织（SAT）测量的研究样本库中，分析血浆 25(OH)D 浓度。研究对象为年龄 8 至 18 岁的健康青少年志愿者。
共纳入 183 名研究志愿者（平均±标准差；年龄 12.6±2.2 岁；98 名白人，98 名男性，92 名肥胖）。对 HbA1c、空腹血糖和胰岛素、胰岛素敏感性和 DI 进行四分位分析，发现白人青少年中，血浆 25(OH)D 四分位之间不存在差异。在黑人青少年中，调整任何肥胖指标（BMI 或脂肪量或 VAT 或 SAT）后，观察到 25(OH)D 最高四分位组中胰岛素敏感性和 DI 较高的显著性消失。当调整肥胖程度时，25(OH)D 非缺乏（≥20ng/mL）和缺乏（＜20ng/mL）黑人青少年之间的胰岛素敏感性差异（9.4±1.2 比 5.6±0.5mg/kg/min/μU/mL；P=0.006）也被否定。
在健康青少年中，血浆 25(OH)D 浓度与血糖稳态和体内胰岛素敏感性及β细胞功能的参数无独立关系，也与胰岛素敏感性无关。在存在糖代谢异常的青少年中，这种关系是否不同，以及维生素 D 优化是否能提高胰岛素敏感性和β细胞功能，仍有待确定。
