Effect of vegetarian dietary patterns on cardiometabolic risk factors in diabetes: A systematic review and meta-analysis of randomized controlled trials

Clin Nutr. 2019 Jun;38(3):1133-1145. doi: 10.1016/j.clnu.2018.05.032. Epub 2018 Jun 13.


Background & aims: To update the European Association for the Study of Diabetes (EASD) clinical practice guidelines for nutrition therapy, we conducted a systematic review and meta-analysis of randomized controlled trials to summarize the evidence for the effect of vegetarian dietary patterns on glycemic control and other established cardiometabolic risk factors in individuals with diabetes.

Methods: We searched MEDLINE, EMBASE, and Cochrane databases through February 26, 2018 for randomized controlled trials ≥3 weeks assessing the effect of vegetarian dietary patterns in individuals with diabetes. The primary outcome was HbA1c. Secondary outcomes included other markers of glycemic control, blood lipids, body weight/adiposity, and blood pressure. Two independent reviewers extracted data and assessed risk of bias. Data were pooled by the generic inverse variance method and expressed as mean differences (MD) with 95% CIs. Heterogeneity was assessed (Cochran Q statistic) and quantified (I2 statistic). The overall certainty of the evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

Results: Nine trials (n = 664 participants) met the eligibility criteria. Vegetarian dietary patterns significantly lowered HbA1c (MD = -0.29% [95% CI: -0.45, -0.12%]), fasting glucose (MD = -0.56 mmol/L [95% CI: -0.99, -0.13 mmol/L]), LDL-C (MD = -0.12 mmol/L [95% CI: -0.20, -0.04 mmol/L]), non-HDL-C (MD = -0.13 mmol/L [95% CI: -0.26, -0.01 mmol/L]), body weight (MD = -2.15 kg [95% CI: -2.95, -1.34 kg]), BMI (MD = -0.74 kg/m2 [95% CI: -1.09, -0.39 kg/m2]) and waist circumference (MD = -2.86 cm [95% CI: -3.76, -1.96 cm]). There was no significant effect on fasting insulin, HDL-C, triglycerides or blood pressure. The overall certainty of evidence was moderate but was low for fasting insulin, triglycerides and waist circumference.

Conclusion: Vegetarian dietary patterns improve glycemic control, LDL-C, non-HDL-C, and body weight/adiposity in individuals with diabetes, supporting their inclusion for diabetes management. More research is needed to improve our confidence in the estimates. CLINICALTRIALS.

Gov identifier: NCT02600377.

Keywords: Cardiometabolic risk; Diabetes; GRADE; Meta-analysis; Systematic review; Vegetarian.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't
  • Systematic Review

MeSH terms

  • Adolescent
  • Adult
  • Blood Pressure / physiology
  • Body Weight / physiology
  • Diabetes Mellitus* / epidemiology
  • Diabetes Mellitus* / physiopathology
  • Diet, Vegetarian*
  • Female
  • Humans
  • Lipids / blood
  • Male
  • Middle Aged
  • Obesity
  • Randomized Controlled Trials as Topic
  • Young Adult


  • Lipids

Associated data

  • ClinicalTrials.gov/NCT02600377

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