Role of vitamin D in the development and progression of diabetic kidney disease: an overview of meta-analyses

Background: The effectiveness of vitamin D supplementation in the progression of diabetic kidney disease (DKD) remains controversial. Our review tries to provide a comprehensive summary of all the relevant articles in the area to assess the association of vitamin D deficiency with the development of DKD and the effect of vitamin D supplementation on the progression of DKD. Methods: PubMed, Embase, Scopus, Cochrane Library and Web of Science were accessed from inception till June 2024 to obtain all the relevant meta-analyses assessing the function of vitamin D in the onset and prognosis of DKD. The summary data were extracted by two independent reviewers. A Measurement Tool to Assess Systematic Reviews (AMSTAR) 2 tool was used for the assessment of the methodological quality of the included meta-analyses. Results: A total of 4579 articles were obtained from 5 databases in the initial search, of which 8 meta-analyses were included for the evidence synthesis. The methodological quality of the retrieved articles ranged from critically low to high. Serum vitamin D levels were significantly correlated with the prevalence of DKD. The review suggested that vitamin D supplementation could help in reducing proteinuria. However, no such changes were observed in other renal function parameters of DKD patients following vitamin D supplementation. Conclusion: The current evidence indicates that vitamin D supplementation could be beneficial in reducing proteinuria among DKD patients. PROSPERO registration number: CRD42022375194.