维生素C对2型糖尿病患者葡萄糖负荷后 血管内皮依赖性功能的保护作用

［摘要］目的探讨维生素C对急性高血糖所致血管内皮功能损伤的防治作用。方法选择正常健康人10例，2型糖尿病（2型DM）患者20例。所有对象均行75 g葡萄糖耐量（OGTT）试验。其中，2型DM患者分为2组，各10例：单纯OGTT组和OGTT + 维生素C组。均分别于OGTT 0，60，120 min采用高分辨血管外超声法检测内皮依赖性血管舒张功能和内皮非依赖性血管舒张功能。结果在OGTT 试验中，单纯OGTT组和OGTT + 维生素C组0，60，120 min内皮依赖性血管舒张功能均明显低于对照组（P＜0.05）。与0 min相比，单纯OGTT组和OGTT + 维生素C组60 min内皮依赖性血管舒张功能明显降低，120 min又明显回升（P＜0.05）。与单纯OGTT组比较，OGTT + 维生素C组60，120 min内皮依赖性血管舒张功能明显增高（P＜0.01）。单纯OGTT组和OGTT + 维生素C组在基础状态下，低密度脂蛋白胆固醇（LDL C）、脂蛋白［Lp（a）］、空腹血糖（FBG）、糖化血红蛋白（HbA1c）与内皮依赖性血管舒张功能呈负相关（P＜0.01）。在OGTT中，单纯OGTT组和OGTT + 维生素C组血糖与内皮依赖性血管舒张功能呈负相关（P＜0.05）。结论高血糖快速抑制内皮依赖性血管舒张功能。提示延长或反复餐后高血糖在糖尿病血管并发症的发生与发展中起重要作用。维生素C对急性高血糖所致内皮功能损伤具有明显防治作用。

Effect of Antioxidant Vitamin Con Vascular Endothelial Function during Acute Hyperglycemia in Patients with Type 2 Diabetes

Objective To investigate the effect of vitamin C on endothelium-dependent arterial dilation during acute hyperglycemia in patients with type 2 diabetes. Methods Ten healthy men,20 men with type 2 diabetes(type 2 DM) were selected.All subjects were performed oral glucose tolerant test(OGTT).Patients with type 2 diabetes were divided into 2 groups: ten patients only took OGTT(OGTT group),and other 10 patients also accepted 2 grams of vitamin C orally(OGTT vitamin C group).Endothelium-dependent arterial dilation and endothelium-independent arterial dilation were measured using high resolution ultrasound technique at the 0,60,and 120 min during the OGTT. Results During the OGTT,the endothelium-dependent arterial dilation at 0,60,120 min in only OGTT group and OGTT vitamin C group were significantly lower than those in control group,respectively(P<0.05).Compared with 0 min,the endothelium-dependent arterial dilation at 60 min were significantly lower in only OGTT group and OGTT vitamin C group(P<0.05),but resumed at 120 min.Compared with only OGTT group,the endothelium-dependent arterial dilation at 60 min and 120 min were significantly increased in OGTT vitamin C group(P<0.05),and there was no difference between the 2 groups at 0 min.At baseline in type 2 DM patients,LDL-C,Lp(a),FBG and HbA1c were negatively related to endothelium-dependent arterial dilation(P<0.01).During OGTT,blood glucose were negatively related to endothelium-dependent arterial dilation in only OGTT group and OGTT vitamin C group(P<0.05). Conclusion Hyperglycemia rapidly suppresses endothelium-dependent arterial dilation,indicating that prolonged and repeated post-prandial hyperglycemia may play an important role in the development of diabetic angiopathy.Vitamin C improves endothelium-dependent arterial dilation during acute hyperglycemia,and this may be related to the role of vitamin C to scavenge oxygen-derived free radicals.