Background Vitamin D deficiency has been implicated in the susceptibility to the metabolic syndrome and a spectrum of conditions, such as obesity and type 2 diabetes mellitus. The present study aimed to quantify the association between vitamin D serum levels and the occurrence of metabolic syndrome components and insulin resistance among Canadian adults.

Methods Vitamin D serum levels and the related clinical data were extracted from 1920 subjects from the Canadian Health Measures Survey, a national survey representing the general Canadian population. The definition of the metabolic syndrome components was based on the National Cholesterol Education Program, Adult Treatment Panel III criteria. Adjusted unconditional logistic regression models were used to estimate the association between vitamin D level quartiles and risk of having metabolic syndrome, as well as the association between plasma vitamin D and insulin resistance (HOMA-IR).

Results Within the survey, 11.4% of the subjects had the metabolic syndrome. Increasing levels of plasma vitamin D were positively correlated with reduced numbers of metabolic syndrome components. Subjects in the highest quartile had significantly lower risk of having metabolic syndrome compared to those in the lowest vitamin D quartile (OR=0.36, 95% CI 0.19 to 0.66). Furthermore, increasing plasma vitamin D levels were associated with lower HOMA-IR scores (β=−0.88, p=0.004) in a fully adjusted linear model.

Conclusion Vitamin D serum levels can predict the occurrence of metabolic syndrome and insulin resistance among Canadian adults.