One year follow-up after a randomized controlled trial of a 130 g/day low-carbohydrate diet in patients with type 2 diabetes mellitus and poor glycemic control

Background & aimsRecently, we conducted a prospective randomized controlled trial (RCT) showing that a 6-month 130g/day low-carbohydrate diet (LCD) reduced HbA1c and BMI more than a calorie restricted diet (CRD). [1] To assess whether the benefits of the LCD persisted after the intensive intervention, we compared HbA1c and BMI between the LCD and CRD groups at 1 year after the end of the 6-month RCT.MethodsFollowing the end of the 6-month RCT, patients were allowed to manage their own diets with periodic outpatient visits. One year later, we analyzed clinical and nutrition data.ResultsOf the 66 participants in the original study, 27 in the CRD group and 22 in the LCD group completed this trial. One year after the end of the original RCT, the carbohydrate intake was comparable between the groups (215 [189–243]/day in the CRD group and 214 (176–262) g/day in the LCD group). Compared with the baseline data, HbA1c and BMI were decreased in both groups (CRD: HbA1c -0.4 [-0.9 to 0.3] % and BMI -0.63 [-1.20 to 0.18] kg/m2; LCD: HbA1c -0.35 [-1.0 to 0.35] % and BMI -0.77 [-1.15 to -0.12] kg/m2). There were no significant differences in HbA1c and BMI between the groups.ConclusionsOne year after the diet therapy intervention, the beneficial effect of the LCD on reduction of HbA1c and BMI did not persist in comparison with CRD. However, combining the data of both groups, significant improvements in HbA1c and BMI from baseline were observed. Although the superiority of the LCD disappeared 1 year after the intensive intervention, these data suggest that well-constructed nutrition therapy programs, both CRD and LCD, were equally effective in improving HbA1c for at least 1 year.Trial registrationUniversity Hospital Medical Information Network (UMIN) ID000010663

研究背景与目的：近期我们开展了一项前瞻性随机对照试验（randomized controlled trial, RCT），结果显示，相较于热量限制饮食（calorie restricted diet, CRD），为期6个月、每日130g的低碳水化合物饮食（low-carbohydrate diet, LCD）可更显著地降低糖化血红蛋白（HbA1c）与体重指数（body mass index, BMI）[1]。为评估强化干预后低碳水化合物饮食的获益是否持续存在，本研究在6个月前瞻性随机对照试验结束后1年，对比了两组受试者的糖化血红蛋白与体重指数水平。

研究方法：6个月前瞻性随机对照试验结束后，允许受试者自行管理饮食，并定期前往门诊随访。1年后，我们对临床与营养数据进行了分析。

研究结果：初始研究共纳入66名受试者，其中热量限制饮食组27名、低碳水化合物饮食组22名完成了本次随访试验。初始试验结束后1年，两组的碳水化合物摄入量无显著差异（CRD组：215[189~243]g/日，LCD组：214(176~262)g/日）。与基线数据相比，两组的糖化血红蛋白与体重指数均有所下降（CRD组：糖化血红蛋白 -0.4[-0.9~0.3]%，体重指数 -0.63[-1.20~0.18]kg/m²；LCD组：糖化血红蛋白 -0.35[-1.0~0.35]%，体重指数 -0.77[-1.15~-0.12]kg/m²）。两组间的糖化血红蛋白与体重指数无显著差异。

研究结论：饮食干预结束后1年，与热量限制饮食相比，低碳水化合物饮食对糖化血红蛋白与体重指数的改善获益并未持续存在。但合并两组数据后可见，与基线相比，受试者的糖化血红蛋白与体重指数均得到了显著改善。尽管强化干预1年后，低碳水化合物饮食的优势不复存在，但本研究数据表明，设计完善的营养治疗方案（无论是热量限制饮食还是低碳水化合物饮食），至少在1年内均可有效改善糖化血红蛋白水平。

试验注册：大学医院医疗信息网络（University Hospital Medical Information Network, UMIN）编号：000010663