The Effect of Vitamin D on Inflammation and Dyslipidemia in Type 2 Diabetes Mellitus: Protocol for a Systematic Review and Meta-analysis of Randomized Controlled Trials

Background: Type 2 diabetes mellitus is a chronic disease that contributes to an increasing global burden on the health system. It has a high chance of leading to macrovascular complications and cardiovascular disease. As an inflammatory condition, it would be essential to target inflammatory pathways when developing therapeutic drugs for type 2 diabetes mellitus. Objective: We aimed to evaluate the effect of vitamin D on markers of inflammation and lipid profile among adult patients with diabetes. Methods: A systematic review will seek studies published on Embase, Google Scholar, PubMed, Web of Science, and Science Direct. This planned systematic review and meta-analysis will be limited to randomized controlled trials; moreover, the search will include published studies regarding the effects of vitamin D on pro-inflammatory cytokines and lipid profiles. The review will include studies published from inception until December 30, 2022. The study identification and selection will be based on the eligibility criteria by 2 independent reviewers. Additionally, a meta-analysis will only be performed if more than 2 studies are available and explore the same outcomes, and this will be analyzed using RevMan (version 5.4.1). The quality and risk of bias will be assessed following the Cochrane risk of bias tool and Jadad checklist. Results: The process for searching literature review has already started, and this is conducted independently by 2 reviewers using a predefined eligibility and "participants, intervention, comparator, and outcome" criteria. This systematic review and meta-analysis will not require any direct involvement of patients and the public; thus, no ethical approval was required.Conclusions: The findings obtained from the proposed study will be presented in scientific seminars, journal clubs, and Trial Registration: International Platform of Registered Systematic Review and Meta-analysis Protocols INPLASY202260022; International Registered Report Identifier (IRRID): PRR1-10.2196/42193