Background

Vitamin D deficiency has recently evolved as a highly prevalent situation affecting almost every third children worldwide. The impact of vitamin D on cardiovascular health in children remains unclear and recent studies investigating relations between them obtained inconsistent results. We aimed to examine the associations between 25-hydroxyvitamin D [25(OH)D] concentrations and cardiometabolic risk factors, and assessed the possible effect modification of obesity on the associations using a nationwide sample.

Methods

A cross-sectional sample of 6091 children aged 6-18 years was obtained using cluster sampling method. The 25(OH)D concentrations, waist to height ratio, blood pressure, blood lipids, fasting blood glucose (FBG), and insulin were determined. Adjusted odds ratios and multiplicative or additive interaction were calculated to assess the associations and effect modification.

Results

Triglycerides, FBG, insulin, and Homeostasis model assessment-insulin resistance were inversely associated with 25(OH)D concentrations (p <0.05) in both genders. The likelihoods of having hyperglycemia (OR: 1.47; 95% CI: 1.26-1.70) were significantly higher in the vitamin D insufficient individuals than those with adequate vitamin D after multivariable adjustment. Moreover, girls with insufficient vitamin D had significantly higher risk of hypertension and high TC than those with adequate vitamin D, which was not observed in boys. 32% (95% CI: 0.14-0.51) of the increased odds of hyperglycemia can be explained by the interaction between insufficient vitamin D and obesity (including overweight).

Conclusions

Vitamin D insufficiency is associated with increased risk of various cardiometabolic risk factors in Chinese children and has a synergistic effect on hyperglycemia with obesity.