Aims/hypothesis

Weight reduction is fundamental for type 2 diabetes management and remission, but uncertainty exists over which diet type is best to achieve and maintain weight loss. We evaluated dietary approaches for weight loss, and remission, in people with type 2 diabetes to inform practice and clinical guidelines.

Methods

First, we conducted a systematic review of published meta-analyses of RCTs of weight-loss diets. We searched MEDLINE (Ovid), PubMed, Web of Science and Cochrane Database of Systematic Reviews, up to 7 May 2021. We synthesised weight loss findings stratified by diet types and assessed meta-analyses quality with A Measurement Tool to Assess Systematic Reviews (AMSTAR) 2. We assessed certainty of pooled results of each meta-analysis using Grading of Recommendations, Assessment, Development and Evaluations (GRADE) (PROSPERO CRD42020169258). Second, we conducted a systematic review of any intervention studies reporting type 2 diabetes remission with weight-loss diets, in MEDLINE (via PubMed), Embase and Cochrane Central Register of Controlled Trials, up to 10 May 2021. Findings were synthesised by diet type and study quality (Cochrane Risk of Bias tool 2.0 and Risk Of Bias In Non-randomised Studies – of Interventions [ROBINS-I]), with GRADE applied (PROSPERO CRD42020208878).

Results

We identified 19 meta-analyses of weight-loss diets, involving 2–23 primary trials (n = 100–1587), published 2013–2021. Twelve were ‘critically low’ or ‘low’ AMSTAR 2 quality, with seven ‘high’ quality. Greatest weight loss was reported with very low energy diets, 1.7–2.1 MJ/day (400–500 kcal) for 8–12 weeks (high-quality meta-analysis, GRADE low), achieving 6.6 kg (95% CI −9.5, −3.7) greater weight loss than low-energy diets (4.2–6.3 MJ/day [1000–1500 kcal]). Formula meal replacements (high quality, GRADE moderate) achieved 2.4 kg (95% CI −3.3, −1.4) greater weight loss over 12–52 weeks. Low-carbohydrate diets were no better for weight loss than higher-carbohydrate/low-fat diets (high quality, GRADE high). High-protein, Mediterranean, high-monounsaturated-fatty-acid, vegetarian and low-glycaemic-index diets all achieved minimal (0.3–2 kg) or no difference from control diets (low to critically low quality, GRADE very low/moderate). For type 2 diabetes remission, of 373 records, 16 met inclusion criteria. Remissions at 1 year were reported for a median 54% of participants in RCTs including initial low-energy total diet replacement (low-risk-of-bias study, GRADE high), and 11% and 15% for meal replacements and Mediterranean diets, respectively (some concerns for risk of bias in studies, GRADE moderate/low). For ketogenic/very low-carbohydrate and very low-energy food-based diets, the evidence for remission (20% and 22%, respectively) has serious and critical risk of bias, and GRADE certainty is very low.

Conclusions/interpretation

Published meta-analyses of hypocaloric diets for weight management in people with type 2 diabetes do not support any particular macronutrient profile or style over others. Very low energy diets and formula meal replacement appear the most effective approaches, generally providing less energy than self-administered food-based diets. Programmes including a hypocaloric formula ‘total diet replacement’ induction phase were most effective for type 2 diabetes remission. Most of the evidence is restricted to 1 year or less. Well-conducted research is needed to assess longer-term impacts on weight, glycaemic control, clinical outcomes and diabetes complications.

Graphical abstract

中文翻译：

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2型糖尿病成人体重管理的饮食：已发表的荟萃分析的综合评价和糖尿病缓解饮食试验的系统评价

目标/假设

减轻体重是 2 型糖尿病管理和缓解的基础，但对于哪种饮食类型最能实现和维持体重减轻存在不确定性。我们评估了 2 型糖尿病患者体重减轻和缓解的饮食方法，为实践和临床指南提供信息。

方法

首先，我们对已发表的减肥饮食随机对照试验荟萃分析进行了系统评价。我们搜索了截至 2021 年 5 月 7 日的 MEDLINE (Ovid)、PubMed、Web of Science 和 Cochrane 系统评价数据库。我们综合了按饮食类型分层的减肥结果，并使用评估系统评价的测量工具 (AMSTAR) 评估了荟萃分析质量) 2. 我们使用建议分级、评估、开发和评估 (GRADE) (PROSPERO CRD42020169258) 评估了每个荟萃分析汇总结果的确定性。其次，我们对截至 2021 年 5 月 10 日在 MEDLINE（通过 PubMed）、Embase 和 Cochrane Central Register of Controlled Trials 中报告通过减肥饮食缓解 2 型糖尿病的任何干预研究进行了系统评价。

结果

我们确定了 19 项关于减肥饮食的荟萃分析，涉及 2-23 项初步试验（n = 100–1587)，2013–2021 年出版。十二个是“极低”或“低”的 AMSTAR 2 质量，七个是“高”质量。据报道，极低能量饮食的体重减轻最大，1.7-2.1 MJ/天（400-500 kcal），持续 8-12 周（高质量荟萃分析，GRADE 低），达到 6.6 kg (95% CI -9.5, −3.7) 比低能量饮食更能减轻体重（4.2–6.3 MJ/天 [1000–1500 kcal]）。配方餐替代品（高质量，GRADE 中等）在 12-52 周内体重减轻了 2.4 公斤（95% CI -3.3，-1.4）。低碳水化合物饮食在减肥方面并不比高碳水化合物/低脂肪饮食（高质量，高等级）更好。高蛋白、地中海、高单不饱和脂肪酸、素食和低血糖指数饮食均达到最低（0.3-2 公斤）或与对照饮食无差异（低至极低质量，GRADE 极低/中等） . 对于 2 型糖尿病缓解，在 373 条记录中，16 条符合纳入标准。据报道，随机对照试验中 54% 的参与者在 1 年时缓解，包括初始低能量全饮食替代（低偏倚风险研究，GRADE 高），以及 11% 和 15% 的膳食替代和地中海饮食，分别（对研究偏倚风险的一些担忧，GRADE 中/低）。对于生酮/极低碳水化合物和极低能量食物为基础的饮食，缓解的证据（分别为 20% 和 22%）具有严重和严重的偏倚风险，并且 GRADE 确定性非常低。代餐和地中海饮食分别为 11% 和 15%（一些对研究偏倚风险的担忧，GRADE 中/低）。对于生酮/极低碳水化合物和极低能量食物为基础的饮食，缓解的证据（分别为 20% 和 22%）具有严重和严重的偏倚风险，并且 GRADE 确定性非常低。代餐和地中海饮食分别为 11% 和 15%（一些对研究偏倚风险的担忧，GRADE 中/低）。对于生酮/极低碳水化合物和极低能量食物为基础的饮食，缓解的证据（分别为 20% 和 22%）具有严重和严重的偏倚风险，并且 GRADE 确定性非常低。

结论/解释

已发表的关于 2 型糖尿病患者体重管理的低热量饮食的荟萃分析不支持任何特定的常量营养素分布或风格。极低能量饮食和配方代餐似乎是最有效的方法，通常比自我管理的基于食物的饮食提供更少的能量。包括低热量配方“全饮食替代”诱导阶段的计划对 2 型糖尿病的缓解最为有效。大多数证据仅限于 1 年或更短时间。需要进行良好的研究来评估对体重、血糖控制、临床结果和糖尿病并发症的长期影响。

图形概要