Correlation of serum vitamin D level with metabolic syndrome in patients with type 2 diabetes mellitus

Objective To investigate the relationship between serum 25-hydroxyvitamin D [25(OH)D] level and the risk of metabolic syndrome (MS) and its components in patients with type 2 diabetes mellitus. Methods Clinical data of 796 type 2 diabetic inpatients in the Department of Endocrinology, the Ninth People′s Hospital, Shanghai Jiaotong University School of Medicine, from January 2017 to December 2018 were enrolled. These patients were divided into MS group (n=541) and non-MS group (n=255). The association of serum vitamin D level and metabolic syndrome was investigated. Results The level of 25(OH)D in MS group was significantly lower than that in non-MS group (P<0.05). According to 25(OH)D 20 ng/ml as the borderline of vitamin D deficiency, the rate of 25(OH)D deficiency in MS group was significantly higher than that in non-MS group (P<0.01). Serum 25(OH)D levels in patients with type 2 diabetes were negatively correlated with smoking, body mass index, systolic blood pressure, diastolic blood pressure, waist circumference, triglyceride, and low density lipoprotein-cholesterol levels (all P<0.05). Multiple logistic regression analysis showed that 25(OH)D was an independent protective factor for MS in patients with type 2 diabetes. These patients were divided into 4 subgroups according to 25(OH)D levels [Q1: 0-10 ng/ml (n=24), Q2: 10-20 ng/ml (n=417), Q3: 20-30 ng/ml (n=117), Q4≥30 ng/ml(n=18)]. Logistic regression showed that the risk ratios (OR) of the metabolic syndrome in the Q2, Q3, and Q4 groups were 0.471, 0.389, and 0.211 respectively, compared with Q1 group (P<0.05). Conclusion Serum 25(OH)D level in type 2 diabetic patients was negatively correlated with the risk of MS. Key words: Vitamin D; 25-hydroxyvitamin; Metabolic syndrome; Diabetes mellitus, type 2