Department of Nephrology, Inonu University Medical Faculty, Malatya, Turkey.
Int Urol Nephrol. 2011 Jun;43(2):527-34. doi: 10.1007/s11255-010-9813-9. Epub 2010 Jul 29.
An association between hypovitaminosis D and insulin resistance has been highlighted. Effects of vitamin D are not only mediated via the vitamin D receptors by active vitamin D metabolites, but 25(OH)D(3) also acts through VDR-independent pathways directly. It was reported that acute and chronic intravenous 1,25-dihydroxycholecalciferol therapy corrects insulin resistance in dialysis patients. There are no studies in patients on dialysis which evaluated relationship between 25(OH)D levels and insulin resistance. The aim of this study was to evaluate relationship between serum 25 (OH) D levels and insulin resistance in nondiabetic patients on peritoneal dialysis (PD).
We studied 53 nondiabetic patients on PD and in 25 age-, gender- and body mass index-matched healthy controls. Insulin resistance was evaluated by the homeostasis model assessment method (HOMA-IR) using fasting glucose and insulin levels. Vitamin D deficiency was defined if 25(OH)D(3) levels are equal to or less to 15 ng/ml.
Mean HOMA-IR index in patients on PD (3.1 ± 3.3) was significantly higher than those of controls (1.7 ± 1.9) (P < 0.05). The mean 25 (OH)D level in PD patients was (21.1 ± 19.0 ng/ml) lower than those of controls (27.5 ± 9.3 ng/ml) (P < 0.05). Twenty-five (47.2%) PD patients had vitamin D deficiency [mean 25(OH)D: 7.2 ± 3.2 ng/ml], and in 28 of them (52.8%) 25 (OH)D levels were more than 15 ng/ml (mean 33.5 ± 18.7 ng/ml). In PD patients with vitamin D deficiency, mean HOMA-IR index (4.2 ± 3.8) was significantly higher than that of PD patients whose 25 (OH)D levels were more than 15 ng/ml (2.2 ± 2.4) (P < 0.05). Twenty-one (84.0%) of PD patients with vitamin D deficiency, and 22 (78.6%) PD patients whose 25 (OH)D levels were more than 15 ng/mL have been receiving active vitamin D compounds for parathyroid hormone (PTH) control (P > 0.05). There was no significant difference between two PD groups according to mean duration of PD, age, gender, PTH, serum calcium, phosphorus, percentage of fat, and body mass index. There was a negative correlation between HOMA-IR index and 25 (OH)D levels in PD patients (r: -0,368, P < 0,05). In multiple regression analyses, the independent predictors of HOMA-IR index were 25(OH)D3 levels, duration of dialysis, and percentage of fat (measured by bioelectrical impedance) in PD patients.
Our findings show a negative correlation of 25(OH)D levels with insulin resistance in PD patients. PD patients with hypovitaminosis D are at higher risk of insulin resistance even if they are on treatment with active vitamin D for PTH control. Further studies are required to explore the relation between vitamin D deficiency and insulin resistance in PD patients.
已经强调了维生素 D 缺乏症与胰岛素抵抗之间的关联。维生素 D 的作用不仅通过活性维生素 D 代谢物的维生素 D 受体介导，而且 25(OH)D(3) 还通过 VDR 非依赖性途径直接作用。据报道，急性和慢性静脉内 1,25-二羟胆钙化醇治疗可纠正透析患者的胰岛素抵抗。在接受透析的患者中，没有研究评估 25(OH)D 水平与胰岛素抵抗之间的关系。本研究旨在评估非糖尿病腹膜透析（PD）患者血清 25(OH)D 水平与胰岛素抵抗之间的关系。
我们研究了 53 名非糖尿病 PD 患者和 25 名年龄、性别和体重指数匹配的健康对照者。使用空腹血糖和胰岛素水平，通过稳态模型评估法（HOMA-IR）评估胰岛素抵抗。如果 25(OH)D(3) 水平等于或低于 15ng/ml，则定义为维生素 D 缺乏症。
PD 患者的 HOMA-IR 指数（3.1±3.3）明显高于对照组（1.7±1.9）（P<0.05）。PD 患者的平均 25(OH)D 水平（21.1±19.0ng/ml）低于对照组（27.5±9.3ng/ml）（P<0.05）。25（47.2%）名 PD 患者存在维生素 D 缺乏症[平均 25(OH)D：7.2±3.2ng/ml]，其中 28 名（52.8%）患者 25(OH)D 水平超过 15ng/ml（平均 33.5±18.7ng/ml）。在维生素 D 缺乏的 PD 患者中，平均 HOMA-IR 指数（4.2±3.8）明显高于 25(OH)D 水平超过 15ng/ml 的 PD 患者（2.2±2.4）（P<0.05）。21（84.0%）名维生素 D 缺乏的 PD 患者和 22（78.6%）名 25(OH)D 水平超过 15ng/ml 的 PD 患者一直在接受活性维生素 D 化合物以控制甲状旁腺激素（PTH）（P>0.05）。根据 PD 患者的平均 PD 持续时间、年龄、性别、PTH、血清钙、磷、脂肪百分比和体重指数，两组 PD 患者之间没有显著差异。PD 患者的 HOMA-IR 指数与 25(OH)D 水平之间存在负相关（r：-0.368，P<0.05）。在多元回归分析中，PD 患者 HOMA-IR 指数的独立预测因子是 25(OH)D3 水平、透析持续时间和脂肪百分比（通过生物电阻抗测量）。
我们的研究结果表明，PD 患者的 25(OH)D 水平与胰岛素抵抗呈负相关。即使 PD 患者正在接受活性维生素 D 治疗以控制甲状旁腺激素，维生素 D 缺乏症的患者仍存在更高的胰岛素抵抗风险。需要进一步研究来探讨 PD 患者中维生素 D 缺乏症与胰岛素抵抗之间的关系。
