Vitamin D levels are associated with low-density lipoprotein cholesterol in Chinese children with type 1 diabetes

Objective There is an increased level of low-density lipoprotein cholesterol (LDL-C)in children with type 1 diabetes mellitus(T1DM). In addition, the Vitamin D level in T1DM patients is usually below the normal reference range. The aim of this study was to explore the relationship between Vitamin D levels and LDL-C in Chinese children with T1DM. Methods A retrospective cross-sectional study was conducted in the Endocrine inpatient wards of Tianjin Children’s Hospital, 143 children with T1DM were included. The related clinical and laboratory examinations, including anthropometric parameters, lipid profiles, and Vitamin D levels, were collected in all subjects. Results The univariate analysis results did not show a significant correlation between Vitamin D levels and LDL-C (P=0.634). Furthermore, a nonlinear relationship was observed between Vitamin D levels and LDL-C by smooth curve fitting after adjusting for potential confounders. A multivariate piecewise linear regression model revealed a significant negative association between LDL-C and Vitamin D levels when LDL-C was greater than 3.1 mmol/L(β -2.9, 95% CI -5.4,-0.5; P=0.022). However, we did not observe a significant relationship between LDL-C and Vitamin D levels when LDL-C was lower than 3.1 mmol/L(β 2.4, 95% CI -0.2,5.1; P=0.076).Conclusions This study identified a nonlinear relationship between Vitamin D levels and LDL-C independent of other potential confounding factors, suggesting that the deficiency or insufficiency of Vitamin D in T1DM children with high LDL-C levels should be considered, especially LDL-C is higher than 3.1 mmol/L, which provides evidence of the timing about Vitamin D supplementation in T1DM children.