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

<b><i>Introduction:</i></b> 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. <b><i>Methods:</i></b> 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. <b><i>Results:</i></b> 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 (<i>p</i> = 0.002). <b><i>Conclusion:</i></b> 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.

**引言**：目前仅有少量研究探讨了维生素D、糖尿病（diabetes mellitus, DM）与勃起功能障碍（erectile dysfunction, ED）三者间的关联，且尚无相关荟萃分析（meta-analysis）对该类研究数据进行合并整合。本研究的核心目的为探究合并勃起功能障碍的糖尿病患者的血清维生素D水平变化情况。
**方法**：本研究开展了全面的文献检索，检索词包括“勃起功能障碍”、“糖尿病”及“维生素D”。检索数据库涵盖Cochrane图书馆、PubMed及Web of Science，检索时限为建库至2021年9月30日。最终共有4项研究符合本荟萃分析的纳入标准。
**结果**：针对纳入的研究数据，本研究计算了加权均数差（weighted mean difference）及其对应的95%置信区间（95% confidence interval）。结果显示，合并勃起功能障碍的糖尿病患者的维生素D水平较单纯糖尿病患者显著降低（差值为12.5 nmol/mL，*p*=0.002）。
**结论**：本项全新的荟萃分析提示，维生素D或可作为合并勃起功能障碍的糖尿病患者的危险因素，该结果可为合并勃起功能障碍的糖尿病的治疗与预防提供全新思路。