Supplementary Material for: Serum Vitamin D Level and Erectile Dysfunction in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis

Introduction: A few studies involved the relationship between vitamin D and diabetes mellitus (DM) with erectile dysfunction (ED), and no meta-analysis was conducted to pool these data. The main purpose of our study was to examine the changes in serum vitamin D levels in patients with DM combined with ED. Methods: An extensive search was performed, including the following words: “erectile dysfunction,” “diabetes,” and “vitamin D.” Databases, including Cochrane Library, PubMed, and Web of Science, were retrieved to identify studies published up to September 30, 2021. Four studies were eligible for our meta-analysis. Results: The weighted mean difference and their corresponding 95% confidence intervals were calculated to the data we selected. The results showed that the level of vitamin D in DM with ED was significantly lower (12.5 nmol/mL) than patients with diabetes alone (p = 0.002). Conclusion: Our novel meta-analysis suggests that vitamin D may be a risk factor for DM with ED, which can provide a new idea for the treatment and prevention of DM with ED.