目的 探究2型糖尿病患者血浆维生素D水平与系统免疫炎症指数（SII）的关联性。 方法 本研究为横断面研究，选取2018年1月至2023年6月期间在广西医科大学第一附属医院住院接受治疗的2型糖尿病患者作为研究对象，收集患者的一般人口学资料、既往病史、体格检测和实验室检查等数据。按照维生素D水平分成3组（缺乏组、不足组和充足组）。采用多元线性回归模型探索维生素D与SII的关联性。采用限制性立方样条模型分析维生素D与SII的非线性剂量反应关系。 结果 本研究共纳入5 716例2型糖尿病患者。SII在不同维生素D水平组有显著差异（P < 0.05），缺乏组SII最高。多元线性回归分析结果显示，调整性别、年龄、采血季节、体质量指数、高血压、血脂异常、慢性肾脏病等混杂因素后，维生素D水平与SII呈负相关（β = -2.68，95%CI：-3.56 ~ -1.81，P < 0.001），与缺乏组相比，充足组SII降低（β = -78.42，95%CI：-137.90 ~ -18.93，P = 0.01）。非线性立方样条模型表明维生素D水平和SII存在非线性剂量反应关系（P < 0.001）。 结论 2型糖尿病患者血浆维生素D水平与SII呈负相关。

Objective To investigate the correlation between plasma vitamin D levels and a novel inflammatory marker， the systemic immune-inflammatory index （SII）， in patients with type 2 diabetes. Methods This study adopted a cross-sectional design， in which patients diagnosed with type 2 diabetes who were admitted to the First Affiliated Hospital of Guangxi Medical University were enrolled as study participants. Data on demographic characteristics， medical history， physical examination findings， and laboratory test results were systematically collected. Participants were categorized into three groups based on their serum vitamin D levels： deficient， insufficient， and sufficient. The relationship between vitamin D levels and the SII was evaluated using a multivariate linear regression model. Additionally， a restricted cubic spline model was employed to assess the nonlinear dose-response association between vitamin D levels and SII. Results This study enrolled a total of 5，716 patients with type 2 diabetes. A statistically significant difference in the SII was observed across groups with varying vitamin D levels （P < 0.05）， with the highest SII value found in the vitamin D-deficient group. Multivariate linear regression analysis revealed that， after adjusting for potential confounding factors including gender， age， season of blood collection， body mass index， hypertension， dyslipidemia， and chronic kidney disease， vitamin D levels were negatively associated with SII （β = -2.68， 95%CI： -3.56 to -1.81， P < 0.001）. Compared with the vitamin D-deficient group， the vitamin D-sufficient group exhibited significantly lower SII levels （β = -78.42， 95%CI： -137.90 to -18.93， P = 0.01）. Furthermore， the restricted cubic spline model indicated a nonlinear dose-response relationship between vitamin D levels and SII （P < 0.001）. Conclusion There is a significant inverse correlation between plasma vitamin D levels and the SII in patients with type 2 diabetes.