Study on serum vitamin A level in patients with type 1 diabetes: A systematic review and meta-analysis.

Background: There is controversy about the relationship between type 1 diabetes and vitamin A (VA) levels in the body. Through meta-analysis, the results of related studies can be aggregated to more accurately estimate the relationship between type 1 diabetes mellitus (T1DM) patients and the level of VA in the body.

Methods: Our purpose is to review the study to investigate VA levels in type T1DM patients and to provide recommendations for future studies. Until January 2024, we searched the National Library of Medicine (PubMed), Cochrane Library, Embase Databases, Web of Sciences, Scopus, China National Knowledge Infrastructure (CNKI), VIP databases (VIP) and WAN FANG databases. After a systematic search, 8 case-control studies were included in our meta-analysis. In the process of data inclusion and extraction, the 2 reviewers selected literature independently of each other. In this study, RevMan5.3 software was used for meta-analysis.

Results: Eight case-control studies involving 689 participants were screened. The results after meta-analysis showed that there was a significant difference in serum VA between the patients with T1DM and the control group (standardized mean difference [SMD] = -0.82, 95% CI [-1.29, -0.36], P < .001, random effects model) with significant heterogeneity among these studies (P < .001, I2 = 84%). Similarly, the difference in the high-performance liquid chromatography (HPLC) subgroup on serum VA (SMD = -0.99, 95% CI [-1.60, -0.38], P = .002) as well as the difference in the countries of Asia and Europe subgroup on serum VA (SMD = -0.60, 95% CI [-1.15, -0.05], P = .03; SMD = -1.06, 95% CI [-1.88, -0.24], P = .01) were suggested to be statistically significant. A significant result was also observed in the National Diabetes Data Group (NDDG) criteria subgroup (SMD = -0.48, 95% CI [-0.85, -0.12]).

Conclusion: Serum VA levels seem to have decreased in T1DM patients. Further research is needed to strengthen this finding and clarify possible impact mechanisms.