Two recent papers confirm the benefits of plant-based eating for diabetes.
The first, a systematic review and meta-analysis of randomised controlled trials, examined the effect of vegetarian dietary patterns on glycaemic control and other cardiometabolic risk factors in individuals with diabetes. Nine studies, including 664 predominately middle-aged, overweight or obese participants with diabetes, controlled by medications (including oral antihyperglycaemic agents, insulin, lipid lowering agents and/ or antihypertensive agents) were included. The types of vegetarian patterns examined included vegan through to lacto-ovo-vegetarian. Across the studies follow-up was a median duration of 12 weeks.
Compared to a non-vegetarian dietary pattern, vegetarian patterns showed significant improvements in markers for diabetes: HbA1c (mean difference of -0.29%); glycaemic control as assessed by fasting glucose (mean difference of -0.56mmol/L); blood lipids as assessed by LDL-C (mean difference of -0.12mmol/L) and non-HDL-C (mean difference of -0.13mmol/L); and body weight/ adiposity, assessed by body weight (mean difference of -2.15kg), BMI (mean difference of -0.74kg/m2) and waist circumference (mean difference of -2.86cm).
The second study investigated whether the level of adherence to a diet high in plant-based foods and low in animal foods was associated with insulin resistance, prediabetes and type 2 diabetes (T2D). This analysis included 6798 participants, average age 62.7 years with a mean BMI of 26.6, from the Rotterdam Study, a prospective population-based cohort in the Netherlands. Adherence to a plant-based diet versus animal diet was assessed using a plant-based index. Food items as measured by a Food Frequency Questionnaire were grouped into 23 food categories, twelve of the categories were plant based and 11 were animal based. Dietary intake (g/day) for each of the 23 food categories were calculated for each participant. Intake for each category was then divided into quintiles. In the plant-based food groups, a score of 4 was given for the highest quintile amount and 0 for the lowest. The 11 animal-based food categories were scored reversely – 0 for the highest amount consumed and 4 for the lowest. These category scores were added up for each participant to create their overall score. Scores ranged from 0 (low adherence to a plant-based diet) to 92 (high adherence to a plant-based diet and low animal-based).
A higher plant-based score was associated with lower insulin resistance (measured at different time-points during the study), lower prediabetes risk (HR = 0.89, median follow-up of 5.7 years) and lower T2D risk (HR = 0.82, median follow-up of 7.3 years) after adjusting for sociodemographic and lifestyle factors.
Whereas previous studies have observed that vegan or vegetarian diets are associated with improved glycaemic control and lower T2D risk, this study has found that total elimination of animal foods is not required. Instead, higher overall adherence to a plant-based diet, which still includes small amounts of animal foods, can bring about benefits.
Findings from these 2 studies are in line with previous studies and strengthen dietary recommendations to adopt a more plant-based diet to help prevent and manage T2D.
- Viguiliouk E, Kendall CW, Kahleova H et al. Effect of vegetarian dietary patterns on cardiometabolic risk factors in diabetes: A systematic review and meta-analysis of randomized controlled trials. Clin Nutr 2018;10.
- Chen Z, Zuurmond MG, van der SN et al. Plant versus animal based diets and insulin resistance, prediabetes and type 2 diabetes: the Rotterdam Study. Eur J Epidemiol 2018;10-0414.