Meta-Analysis of Diabetes and Vegetarians

Compiled by Ginny Messina, MPH, RD

We have updated the article Type 2 Diabetes and Vegan Diets:

A 2017 meta-analysis reviewed 14 studies published in 13 papers (1). Two were cohort studies and the other 12 were cross-sectional.

Vegetarians had a lower incidence of diabetes in eight of the studies while there was no difference in the other five. Based on the pooled analysis of the studies, vegetarians had a 27% lower risk for diabetes compared to omnivores (OR 0.73, 95% CI: 0.61, 0.87).

When the researchers looked at effects in different groups, they found that vegetarian men were less likely to have diabetes than omnivore men, but there was no difference in risk between vegetarian and omnivore women. The researchers also looked at different types of vegetarian diets and found that risk for diabetes was lowest among vegans and lacto-vegetarians. Pesco-vegetarians did not have a lower risk for diabetes compared to omnivores, although semi-vegetarians did.

The main limitation of this meta-analysis is that most of the studies were cross-sectional. In addition, the studies were from diverse populations throughout the world where definitions and composition of vegetarian diets may differ. This might explain why among these studies, the findings were stronger in studies from North America, Europe, and the Western Pacific than in those in Southeast Asia.


1. Lee Y, Park K. Adherence to a Vegetarian Diet and Diabetes Risk: A Systematic Review and Meta-Analysis of Observational Studies. Nutrients. 2017 Jun 14;9(6).

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