The Effect of an Online Plant-Based Dietary Program on Cardiovascular Risk Factors in Persons With Type 2 Diabetes Mellitus: A Randomized Controlled Trial

Persons with Type 2 Diabetes (T2D) are at an increased risk of cardiovascular disease (CVD) and mortality. Dietary changes are recommended by guidelines to treat T2D and reduce risk of CVD. Plant-based diets eliminate certain (i.e. vegetarian diet) or eliminate all animal based products (i.e. vegan diet). Clinical trials with plant-based diets have not looked at incidence of CVD as a (primary) outcome, but at intermediate outcomes of cardiovascular risk. A meta-analysis of 8 trials including 369 persons with T2D found an effect of a plant-based diet on glycated hemoglobin (HbA1c) of -0.29% \[95% CI: -0.45, -0.12%\] relative to mostly (omnivorous) low-fat diets or usual diet. The 95%CI ranged from what the authors had defined as clinically trivial to clinically relevant. For lipids, a network meta-analysis in persons with T2D compared the effect of a plant-based diet to a (omnivorous) low fat diet (274 patients allocated to a plant-based diet vs 2047 patients allocated to low fat diets). Compared to omnivorous low fat diets, the mean effect of plant-based diets on LDL-Cholesterol was -0.33 mmol/L \[95%CI:- 0.55, - 0.12\]. However, the quality of the evidence for this estimate was graded as low, mainly due to imprecision and within-study-bias. Furthermore, plant-based diets might reduce blood pressure (BP). However, while vegetarian diets reduce BP in patients with and without hypertension, for vegan diets the effect was only significant in patients with a systolic BP\>130mmHgz (see section 1.4.3). Additionally, the effect of plant-based diets on inflammation, which might also be causally related to CVD risk in persons with T2D, has not been reported in trials with persons with T2D. Furthermore, most clinical trials of plant-based diets in persons with T2D have used resource intensive interventions, like weekly group meetings and cooking sessions. The effect of an online plant-based dietary intervention, which is more scalable, has not been reported in clinical trials. Lastly, factors influencing adherence in these trials have not been reported. In summary, plant-based diets likely lower CVD risk by lowering HbA1c, LDL cholesterol and potentially blood pressure in persons with T2D. However, estimated effect sizes are imprecise and the effect on inflammation is still unknown. Furthermore, trials to date have used resource intensive interventions. Thus, the present trial aims to study the effect of a primarily online plant-based dietary program on (cardio)vascular risk factors in persons with T2D. Additionally, adherence and factors influencing adherence will be investigated. Participants will be randomized to the intervention or control group. The intervention group will be guided to transition to a plant-based dietary pattern using an online platform and online sessions. Researchers will compare the intervention group to the control group, that continues with usual diet, to see if the cardiovascular risk profile of the intervention group improves.