Improved Management of Type 2 Diabetes With a Plant-Based Diet Compared to a Conventional Diabetes Diet

Background: Diabetes is a rapidly growing epidemic that, to a degree, is both caused by and managed with diet. Vegetarian and vegan diets are associated with a reduced risk of diabetes, and have been shown to increase insulin sensitivity and decrease body weight. This study sought to review trials that directly compare a vegetarian or vegan diet to a conventional diabetes diet with the outcome of improved management, as measured by weight loss, reduction in medication use and glycated hemoglobin (HbA1c). Method: An extensive literature search was performed using MEDLINE-OVID, CINAHL, Evidence-Based Medicine Reviews Multifile and Web of Science to include randomized controlled trials (RCTs) directly comparing a vegetarian or vegan diet to a conventional diabetes diet. The following search terms were used: “Diabetes or Diabetes Mellitus or Diabetes Mellitus, Type 2” and “Vegan diet or Diet, vegetarian.” The quality of evidence presented in each article was assessed using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) criteria. Results: Three RCTs were included in the review. Diabetics assigned to the experimental group reduced or stopped hypoglycemic medications significantly more than those in the control group. The effect of diet on HbA1c was not significant in any study based on intention-to-treat analyses, but in sub-group analyses accounting for medication change, the vegan/vegetarian group indicated a greater reduction in two studies. Weight loss was significant within each diet group, and two studies found it to be significantly greater in the vegetarian group. Conclusion: Individuals with type 2 diabetes who participate in vegan and vegetarian diets effectively lose weight and have better glycemic control as measured by medication reduction than those following a conventional diabetes diet. Keywords: diabetes, type 2 diabetes, vegan diet, vegetarian diet, conventional diabetes diet, glycemic control, weight loss, managemen