低碳水化合物饮食对2型糖尿病患者糖代谢的改善作用

Low-carbohydrate diet regulates intestinal microorganisms to improve glucose metabolism in patients with type 2 diabetes mellitus

目的探讨低碳水化合物饮食对2型糖尿病(T2DM)患者肠道微生物和空腹高血糖的影响。方法选择2019年5月至2019年8月我院内分泌科招募的100例T2DM患者为研究对象,患者随机分配到干预饮食组(LCD组,低碳水化合物饮食)或控制饮食组(LFD组)。LFD组患者的饮食为500 g蔬菜/d,100 g主食/餐(300 g/d),3汤匙油/d,两餐之间提供稳定血糖、低血糖指数水果,5种蛋白质(220 mL牛奶、1个鸡蛋、100 g鱼虾、50 g大豆、50 g肉)/d,6 g盐/d。LCD组每天摄入杏仁56 g以取代150 g/d富含碳水化合物的主食,其余饮食方案与LFD组相同。收集所有参与者的粪便标本,取豌豆大小的粪便置入1.5 mL的试管中,立即于−80℃保存。使用QIAAMP^(®)DNA粪便抽提试剂盒进行粪便样本的总DNA提取,随后进行16S rRNA基因测序,对其菌群进行分析。结果LCD组患者肠道微生物群Shannon指数,Chao指数和Simpson指数显著高于LFD组(均P<0.05)。两组患者按照规定饮食3个月后肠道微生物组检测显示,总共有9个门,其中排名前5位的细菌门约占所有细菌的96.00%。LCD组患者以拟杆菌门为主(72.32%),其次为假单胞菌门(13.81%)、变形菌门(8.22%)、梭杆菌门(0.03%)、放线菌门(0.63%)。LFD组患者肠道菌群门水平的细菌组成与LCD组相近。其中,LFD组梭杆菌门丰度(0.35%)高于LCD组(0.03%)。同时,LCD组产单链脂肪酸细菌(Roseburis)和瘤胃球菌的相对丰度升高。两组之间3种主要营养素的总能量和热量比例差异无统计学意义(均P>0.05)。干预3个月时,两组患者的总能量差异无统计学意义(P>0.05)。与LFD组相比,LCD组患者来自碳水化合物的热量减少,而来自脂肪的热量显著增加(均P<0.05)。此外,干预后,LCD组患者中有40%来自碳水化合物的热量达到LCD标准,而LFD组患者中有25%来自脂肪的热量达到LFD标准。治疗3个月时,LCD组患者HbA1c下降幅度大于LFD组(P<0.05)。干预期间,LCD组有3例、LFD组有5例患者降糖药物使用量减少,其余受试者无显著变化。结论低碳水化合物饮食可能通过改善T2DM患者肠道菌群区系进一步改善患者的糖代谢。

Objective To observe the effects of low-carbohydrate diet on intestinal microflora and fasting hyperglycemia in patients with type 2 diabetes mellitus(T2DM).Methods A total of 100 T2DM patients recruited in the Endocrinology Department of our hospital from May 2019 to August 2019 were enrolled.The participants were randomly assigned to either the intervention diet group(LCD group)or the control diet group(LFD group).The food for LFD group were 500 g vegetables/day,100 g staple foods/meal(300 g/d),3 tablespoons oil/day,fruits with stable blood sugar and low glycemic index between meals,5 kinds of protein/day(220 mL milk,1 egg,100 g fish and shrimp,50 g soybeans,50 g meat)and 6 g salt/day.The LCD group was given 56 grams of almonds to replace 150 grams of staple diet rich in carbohydrates in a day;the rest of the diet was the same as those for LFD group.The stool samples of all participants were collected and a peasized feces were placed in a 1.5 mL test tube and stored at−80℃immediately.QIAAMP®DNA fecal extraction kit was used to extract total DNA from fecal samples,then 16S rRNA sequencing was performed to analyze the flora.Results The Shannon index,Chao index and Simpson index of intestinal microflora in LCD group were significantly higher than those in LFD respectively.The intestinal microbiome data in the two groups three months after the prescribed diet showed that there were a total of 9 phyla,among which the first five phyla accounted for about 96%of all bacteria.In LCD group,Bacteroides was dominant(72.32%),followed by Pseudomonas(13.81%),Proteus(8.22%),Clostridium(0.03%)and Actinomycetes(0.63%).The bacterial composition at the phylum level in the LFD group was similar to that in the LCD group.The abundance of Clostridium in LFD group(0.35%)was higher than that in LCD group(0.03%).In LCD group,the relative abundances of single chain fatty acid producing bacteria(Roseburis)and Rumencocci increased.There were no significant differences in the total energy and calorie ratio of the three major nutrients between groups(all P>0.05).At 3 months,there was no significant difference in total energy between groups(P>0.05).Compared with the LFD group,the calories from carbohydrates decreased and those from fat increased significantly in the LCD group.After the intervention,40%of the calories from carbohydrates in the LCD group reached the LCD standard,while 25%of the calories from fat in the LFD group reached the LFD standard.After 3 months of treatment,the decrease of HbA1c in LCD group was higher than that in LFD group(P<0.01).During the intervention,the hypoglycemic drugs dose decreased in 3 cases in LCD group and 5 cases in LFD group;there was no significant change in other subjects.Conclusion LCD may further improve glucose metabolism in patients with T2DM by improving intestinal flora.