美国德克萨斯农工大学Bradley C Johnston团队研究了低碳水化合物和极低碳水化合物饮食对2型糖尿病缓解的疗效和安全性。2021年1月13日，该研究发表在《英国医学杂志》上。

为了确定低碳水化合物饮食（LCD）和极低碳水化合物饮食（VLCD）对2型糖尿病患者的疗效和安全性，研究组对CENTRAL、Medline、Embase等大型数据库中从成立到2020年8月25日的文献进行检索，筛选出评估2型糖尿病成人至少12周LCD和VLCD干预的随机临床试验，并进行系统审查和荟萃分析。主要结局是糖尿病的缓解（HbA1c<6.5％或空腹血糖<7.0 mmol / L，无论是否服用糖尿病药物）、体重减轻、HbA1c、空腹血糖和不良事件。次要结局包括与健康相关的生活质量和生化实验室数据。

研究组共检索了14759篇引文，共纳入23项试验（1357名参与者），40.6%的结果被判定为低偏倚风险。在6个月时，与对照饮食相比，LCD的糖尿病缓解率更高（定义为HbA1c<6.5%）。相反，当使用HbA1c<6.5%且不服药的缓解定义时，缓解率有较小但不显著的提高。确定为符合可信度标准的亚组评估表明，在包括使用胰岛素的患者的研究中，LCD的缓解率明显降低。

在12个月时，关于病情缓解的数据很少，从轻微改善到轻微的糖尿病风险增加不等。在6个月时，体重减轻、甘油三酯和胰岛素敏感性均有显著的临床意义改善，12个月时改善程度有所下降。根据可信的分组评估，VLCD在6个月时的减重效果不如限制性较小的LCD。然而，这种影响可以通过坚持饮食来解释。也就是说，与使用VLCD的依从性较差的患者相比，使用LCD的依从性较好的患者其体重在临床上显著降低。参与者6个月时的生活质量没有显著差异，但在12个月时生活质量和低密度脂蛋白胆固醇恶化方面具有临床上重要但无统计学意义的差异。另外，在6个月和12个月时，在不良事件或血脂方面，未发现两组间有显著或临床意义的差异。

总之，根据中低确定性的证据，坚持使用LCD 6个月的糖尿病患者病情有望缓解，而不会产生不良后果。

附：英文原文

Title: Efficacy and safety of low and very low carbohydrate diets for type 2 diabetes remission: systematic review and meta-analysis of published and unpublished randomized trial data

Author: Joshua Z Goldenberg, Andrew Day, Grant D Brinkworth, Junko Sato, Satoru Yamada, Tommy Jnsson, Jennifer Beardsley, Jeffrey A Johnson, Lehana Thabane, Bradley C Johnston

Issue&Volume: 2021/01/13

Abstract:

Objective To determine the efficacy and safety of low carbohydrate diets (LCDs) and very low carbohydrate diets (VLCDs) for people with type 2 diabetes.

Design Systematic review and meta-analysis.

Data sources Searches of CENTRAL, Medline, Embase, CINAHL, CAB, and grey literature sources from inception to 25 August 2020.

Study selection Randomized clinical trials evaluating LCDs (<130 g/day or <26% of a 2000 kcal/day diet) and VLCDs (<10% calories from carbohydrates) for at least 12 weeks in adults with type 2 diabetes were eligible.

Data extraction Primary outcomes were remission of diabetes (HbA1c <6.5% or fasting glucose <7.0 mmol/L, with or without the use of diabetes medication), weight loss, HbA1c, fasting glucose, and adverse events. Secondary outcomes included health related quality of life and biochemical laboratory data. All articles and outcomes were independently screened, extracted, and assessed for risk of bias and GRADE certainty of evidence at six and 12 month follow-up. Risk estimates and 95% confidence intervals were calculated using random effects meta-analysis. Outcomes were assessed according to a priori determined minimal important differences to determine clinical importance, and heterogeneity was investigated on the basis of risk of bias and seven a priori subgroups. Any subgroup effects with a statistically significant test of interaction were subjected to a five point credibility checklist.

Results Searches identified 14759 citations yielding 23 trials (1357 participants), and 40.6% of outcomes were judged to be at low risk of bias. At six months, compared with control diets, LCDs achieved higher rates of diabetes remission (defined as HbA1c <6.5%) (76/133 (57%) v 41/131 (31%); risk difference 0.32, 95% confidence interval 0.17 to 0.47; 8 studies, n=264, I2=58%). Conversely, smaller, non-significant effect sizes occurred when a remission definition of HbA1c <6.5% without medication was used. Subgroup assessments determined as meeting credibility criteria indicated that remission with LCDs markedly decreased in studies that included patients using insulin. At 12 months, data on remission were sparse, ranging from a small effect to a trivial increased risk of diabetes. Large clinically important improvements were seen in weight loss, triglycerides, and insulin sensitivity at six months, which diminished at 12 months. On the basis of subgroup assessments deemed credible, VLCDs were less effective than less restrictive LCDs for weight loss at six months. However, this effect was explained by diet adherence. That is, among highly adherent patients on VLCDs, a clinically important reduction in weight was seen compared with studies with less adherent patients on VLCDs. Participants experienced no significant difference in quality of life at six months but did experience clinically important, but not statistically significant, worsening of quality of life and low density lipoprotein cholesterol at 12 months. Otherwise, no significant or clinically important between group differences were found in terms of adverse events or blood lipids at six and 12 months.

Conclusions On the basis of moderate to low certainty evidence, patients adhering to an LCD for six months may experience remission of diabetes without adverse consequences. Limitations include continued debate around what constitutes remission of diabetes, as well as the efficacy, safety, and dietary satisfaction of longer term LCDs.

DOI: 10.1136/bmj.m4743

Source: https://www.bmj.com/content/372/bmj.m4743