ARS | Publication request: Predicted 25-hydroxyvitamin D score and incident type 2 diabetes in the Framingham Offspring Study

Submitted to: American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 19, 2010
Publication Date: June 1, 2010
Citation: Liu, E., Mckeown, N.M., Pittas, A.G., Meigs, J.B., Economos, C., Booth, S.L., Jacques, P.F. 2010. Predicted 25-hydroxyvitamin D score and incident type 2 diabetes in the Framingham Offspring Study. American Journal of Clinical Nutrition. 91(6):1627-1633.

Interpretive Summary: The relation between vitamin D status and bone health is well established, but there is accumulating evidence that vitamin D might have other functions, including involvement in the development of type 2 diabetes (T2D). There are few prospective studies on the association between vitamin D status and risk of T2D, and evidence from these studies is limited by the use of vitamin D intake or a single measurement of 25(OH)D concentration as a surrogate for usual vitamin D status. Because vitamin D can be synthesized in human skin under sunlight exposure and thereby has seasonal variation, the use of vitamin D intake cannot capture an individual’s overall vitamin D status, whereas a single measurement of 25(OH)D does not take into account the within-person variation across different seasons. In this study we sought to test the hypothesis that vitamin D status is inversely associated with subsequent risk of T2D using a predicted 25(OH)D score, which was derived from known potential determinants of plasma 25(OH)D concentration and aimed to remove the seasonal effect on vitamin D status by holding season constant. We applied this score to each non-diabetic participant at the Framingham Offspring cohort’s fifth examination to assess the association between the predicted 25(OH)D and incidence of T2D. A total of 133 T2D cases were identified over a 7-y average follow-up. In comparison with individuals in the lowest predicted 25(OH)D score at baseline, those in the highest had a 40% lower incidence of T2D. Our findings suggest that higher vitamin D status is associated with decreased risk of T2D. Maintaining optimal 25(OH)D status may be a strategy to prevent the development of T2D.

Technical Abstract: Accumulating evidence suggests that vitamin D is involved in the development of type 2 diabetes (T2D). Our objective was to examine the relation between vitamin D status and incidence of T2D. We used a subsample of 1972 Framingham Offspring Study participants to develop a regression model to predict plasma 25- hydroxyvitamin D [25(OH)D] concentrations from age, sex, body mass index, month of blood sampling, total vitamin D intake, smoking status, and total energy intake. Using this model, we calculated the predicted 25(OH)D score for each nondiabetic participant at the cohort’s fifth examination to assess the association between the predicted 25(OH)D score and incidence of T2D by using Cox proportional hazards models. A total of 133 T2D cases were identified over a 7-y average follow-up. In comparison with individuals in the lowest tertile of the predicted 25(OH)D score at baseline, those in the highest tertile had a 40% lower incidence of T2D after adjustment for age, sex, waist circumference, parental history of T2D, hypertension, low HDL cholesterol, elevated triglycerides, impaired fasting glucose, and Dietary Guidelines for Americans Adherence Index score (hazard ratio: 0.60; 95% CI: 0.37, 0.97; P for trend = 0.03). Our findings suggest that higher vitamin D status is associated with decreased risk of T2D.Maintaining optimal 25(OH)D status may be a strategy to prevent the development of T2D.