Effect of diet on the management of hypertension and type 2 diabetes mellitus in adults from low-income and middle-income countries: protocol for a systematic review of randomised controlled trials

Introduction Hypertension and type 2 diabetes mellitus (T2DM) are two highly prevalent non-communicable diseases worldwide, both leading to disability and premature mortality in low-and-middle-income countries (LMICs). Nutritional interventions towards a healthier dietary pattern or food and nutrients intake have an important role on the management of this disease. This systematic review aims to evaluate the effect of nutritional interventions on the management of blood pressure and glycaemia in adults with hypertension and T2DM from LMICs. Methods and analysis We will conduct a systematic review of randomised controlled trials (RCTs) on the effect of nutritional interventions on blood pressure and glycaemia in adult patients with hypertension and T2DM. Literature search will be conducted in MEDLINE, EMBASE, Scopus, Cochrane and Web of Science databases from anytime until April 2024. Nutritional interventions would have been applied in addition to regular or standard treatment, which is prescribed and/or provided by the healthcare system. Studies in English and Spanish will be selected and reviewed by two independent reviewers. Risk of bias will be assessed using the Cochrane tool for RCTs. Heterogeneity and publication bias will be estimated using the I 2 and Egger's test, respectively. Ethics and dissemination Ethics approval was not required for this systematic review, considering there was no direct data collection or participation of patients. The investigators will write a manuscript of the final detailed report with the study development and main findings to be published in a peer- reviewed journal. The main findings may be shared with academia partners and groups working on similar topics in LMICs, in addition to policymakers and authorities in these countries.