Plant-based diet associated with reduced insulin resistance, T2D risk
Individuals who opt for a plant-based diet over an animal-based one may reduce their risk of developing insulin resistance or incident type 2 diabetes (T2D), according to a study from the Netherlands.
The results were based on data of 6,770 individuals who did not have diabetes at baseline (mean age 62 years, 58.7 percent female) from three subcohorts of The Rotterdam Study, a large population-based observational study conducted in Rotterdam, the Netherlands. A total of 642 cases of T2D were diagnosed over a median follow-up period of 7.3 years, as well as 928 cases of pre-diabetes over a median 5.7 years of follow up.
Insulin resistance was determined via HOMA-IR* based on fasting glucose and insulin levels measured at follow ups every 3–5 years and incident T2D determined based on medical records, use of diabetes medications, and/or fasting glucose levels ≥7.0 mmol/L. Dietary intake was assessed using food frequency questionnaires categorized into 23 food groups. Plant-based foods comprised among others, fruits, vegetables, legumes, nuts, sweets, and sugary or alcoholic beverages, while animal-based foods included meat, fish, eggs, and dairy products. Individuals with a diet comprising more plant-based foods and fewer animal-based ones would have a higher score on the plant-based dietary index.
Individuals with a higher score on the plant-based dietary index had a lower risk of incident T2D compared with those with a lower score (adjusted** hazard ratio, 0.87, 95 percent confidence interval [CI], 0.79–0.99; p<0.05 per 10-unit increase on the plant-based dietary index). [European Association for the Study of Diabetes (EASD) 2018, oral presentation 154]
Individuals without T2D who had a higher score on the plant-based dietary index had a lower HOMA-IR score and thus, a reduced risk for insulin resistance (β, -0.05, 95 percent CI, -0.06 to -0.04; p<0.001 per 10-unit increase on the plant-based dietary index).
Subgroup analyses that excluded patients with other chronic diseases did not affect the findings, nor did excluding each of the 23 groups one at a time.
“Vegan or vegetarian diets have been linked to improved glycaemic control among diabetes patients and also a lower diabetes risk in general populations,” said study author Assistant Professor Trudy Voortman from Erasmus University Medical Center Rotterdam, in Rotterdam, the Netherlands, who presented the findings at the recent EASD meeting. [Cardiovasc Diagn Ther 2014;4:373-382; Nutr Metab Cardiovasc Dis 2013;23:292-299]
“We observed that a higher adherence to a more plant-based, less animal-based diet was associated with a lower risk of developing diabetes and also a lower [risk of] insulin resistance,” she said. “These findings suggest a protective role of a more plant-based diet in the development of T2D beyond strict adherence to a vegetarian or vegan diet [and also] strengthen recent dietary recommendations to adopt a more plant-based diet.”
Voortman and co-authors acknowledged that the plant-based diet included “less healthy” options such as sweetened beverages, that would not be recommended in a healthy diet, while foods such as fish that are deemed healthy, were given lower scores as they were animal-based. [Eur J Epidemiol 2018;33:883-893]
However, sensitivity analyses showed that the benefits of a plant-based diet were driven by an increased consumption of healthy plant-based foods and lower consumption of animal-based foods. “This emphasizes that it is important to also consider the quality of plant-based foods consumed, which has important public health implications,” they said.