Vitamin D Levels Are Associated with Risk Factors for Type 2 Diabetes and Metabolic Syndrome in Chinese Youths

Evidence regarding association between vitamin D deficiency and metabolic syndrome (MS) remains controversial and relatively sparse among youth. We aimed to explore the relationship between serum 25-hydroxyvitamin D [25(OH)D] levels and risk factors for type 2 diabetes and MS in Chinese adolescents and young adults. A total of 559 subjects aged 14-28 years with high risk of MS were recruited from the Beijing Child and Adolescent Metabolic Syndrome Study cohort in 2012. All subjects underwent a 2h-oral glucose tolerance test. The concentrations of 25(OH)D, glucose, insulin and lipids were determined. MS was defined by the 2009 harmonized definition. The prevalence of vitamin D deficiency (< 20 ng/ml) was 78.3%. After adjusting for age, gender and visiting season, 25(OH)D levels were negatively correlated with percent body fat, LDL-C, fasting and 2h-glucose levels (all p < 0.05). 25(OH)D levels were significantly lower in subjects with obesity, high TG, type 2 diabetes, or MS, compared to their counterparts, respectively (all p < 0.05). After adjustment for potential confounders including body mass index, subjects in the lowest vs. highest tertile of 25(OH)D levels was 2.5 times more likely to have MS (Odds 95% CI: 1.13-5.45, p < 0.05). Vitamin D deficiency was very common in this young Chinese population with risk for MS. Given the negative association between vitamin D level and cardiometabolic risk factors, effective sun exposure and vitamin D supplementation should be encouraged in youths, particular in those with high MS risk.