英国东安格利亚大学Lee Hooper研究团队的一项最新研究，对ω-3、ω-6和总膳食多不饱和脂肪酸（PUFA）预防和治疗2型糖尿病的效果进行了随机对照试验的系统回顾和荟萃分析。 这一研究成果于2019年8月22日在线发表于《英国医学杂志》。

2型糖尿病是导致死亡的主要原因之一，会增加心血管疾病、失明、肾功能衰竭和下肢截肢的风险。全世界有4亿多成年人患有糖尿病。

该课题组从各大数据库中检索随机对照试验，评估增加α-亚麻酸、长链ω-3、ω-6或总PUFA对糖尿病指标的影响。统计分析包括随机效应荟萃分析和敏感性分析。

该研究共包括83项随机对照试验，10项偏倚总风险较低。长链ω-3对糖尿病的发病风险和葡萄糖代谢指标几乎没有影响。而当补充长链ω-3的剂量超过每日4.4克时，则出现负性结果。而α-亚麻酸、ω-6和总PUFA对糖尿病的影响尚未清楚，但对葡萄糖代谢指标几乎没有影响，除了α-亚麻酸可能会增加空腹胰岛素水平（约7%）。也没有证据表明ω-3/ω-6的比值对糖尿病或葡萄糖代谢有重要影响。

迄今为止，这是研究多不饱和脂肪酸对糖尿病发病率和葡萄糖代谢影响的最广泛的系统综述，证据表明，增加ω-3、ω-6或总PUFA对预防和治疗2型糖尿病几乎没有效果。

附：英文原文

Title: Omega-3, omega-6, and total dietary polyunsaturated fat for prevention and treatment of type 2 diabetes mellitus: systematic review and meta-analysis of randomised controlled trials

Author: Tracey J Brown, senior research associate*,   Julii Brainard, senior research associate*,   Fujian Song, professor in research synthesis,   Xia Wang, honorary research fellow,   Asmaa Abdelhamid, honorary research fellow,   Lee Hooper, reader in research synthesis, nutrition and hydration on behalf of the PUFAH Group

Issue&Volume: 21 August 2019

Abstract: 

Objective To assess effects of increasing omega-3, omega-6, and total polyunsaturated fatty acids (PUFA) on diabetes diagnosis and glucose metabolism.

Design Systematic review and meta-analyses.

Data sources Medline, Embase, Cochrane CENTRAL, WHO International Clinical Trials Registry Platform, Clinicaltrials.gov, and trials in relevant systematic reviews.

Eligibility criteria Randomised controlled trials of at least 24 weeks’ duration assessing effects of increasing α-linolenic acid, long chain omega-3, omega-6, or total PUFA, which collected data on diabetes diagnoses, fasting glucose or insulin, glycated haemoglobin (HbA1c), and/or homoeostatic model assessment for insulin resistance (HOMA-IR).

Data synthesis Statistical analysis included random effects meta-analyses using relative risk and mean difference, and sensitivity analyses. Funnel plots were examined and subgrouping assessed effects of intervention type, replacement, baseline risk of diabetes and use of antidiabetes drugs, trial duration, and dose. Risk of bias was assessed with the Cochrane tool and quality of evidence with GRADE.

Results 83 randomised controlled trials (mainly assessing effects of supplementary long chain omega-3) were included; 10 were at low summary risk of bias. Long chain omega-3 had little or no effect on likelihood of diagnosis of diabetes (relative risk 1.00, 95% confidence interval 0.85 to 1.17; 58 643 participants, 3.7% developed diabetes) or measures of glucose metabolism (HbA1c mean difference −0.02%, 95% confidence interval −0.07% to 0.04%; plasma glucose 0.04, 0.02 to 0.07, mmol/L; fasting insulin 1.02, −4.34 to 6.37, pmol/L; HOMA-IR 0.06, −0.21 to 0.33). A suggestion of negative outcomes was observed when dose of supplemental long chain omega-3 was above 4.4 g/d. Effects of α-linolenic acid, omega-6, and total PUFA on diagnosis of diabetes were unclear (as the evidence was of very low quality), but little or no effect on measures of glucose metabolism was seen, except that increasing α-linolenic acid may increase fasting insulin (by about 7%). No evidence was found that the omega-3/omega-6 ratio is important for diabetes or glucose metabolism.

Conclusions This is the most extensive systematic review of trials to date to assess effects of polyunsaturated fats on newly diagnosed diabetes and glucose metabolism, including previously unpublished data following contact with authors. Evidence suggests that increasing omega-3, omega-6, or total PUFA has little or no effect on prevention and treatment of type 2 diabetes mellitus.

DOI: https://doi.org/10.1136/bmj.l4697

Source: https://www.bmj.com/content/366/bmj.l4697