Vitamin D and risk of developing type 2 diabetes in the SUN project: a prospective cohort study

Abstract

Purpose: Vitamin D deficiency has been associated with multiple chronic diseases, including metabolic disorders such as insulin resistance and type 2 diabetes (T2D). The aim of the study was to analyze the association between validated predicted serum vitamin D status and the risk of developing T2D in a large prospective cohort based on a Mediterranean population.

Methods: The SUN project is a prospective and dynamic Spanish cohort that gathers university graduates who have answered lifestyle questionnaires, including a validated Food Frequency Questionnaire. The association between predicted serum vitamin D and the risk of T2D was assessed through Cox regression models according to quartiles (Q) of predicted vitamin D at baseline. The models were adjusted for potential confounders and sensitivity analyses were performed to ensure the robustness of our findings.

Results: Our study included a total of 18,594 participants and after a total follow-up of 238,078 person-years (median follow-up of 13.5 years), 209 individuals were diagnosed with incident T2D. We found a significant inverse association between predicted levels of serum vitamin D and the risk of developing T2D, after adjusting for potential confounders and performing different sensitivity analyses (hazard ratio Q4 vs. Q1: 0.48, 95% CI 0.26-0.88; p for trend = 0.032).

Conclusion: The outcomes suggest that higher levels of vitamin D at baseline may be associated with a reduced risk of developing T2D.

Keywords: Predicted vitamin D; Prospective cohort; SUN project; Type 2 diabetes.

Fig. 1

Flowchart of participants included in the present analyses. ^aWillett’s energy limits (< 800 kcal/d or > 4000 kcal/d in men and < 500 kcal/d or > 3500 kcal/d in women)

Fig. 2

Restricted cubic splines dose–response pattern: adjusted hazard ratios (HR)* and 95% confidence intervals (CI) for the development of T2D according to predicted serum vitamin D. *Adjusted for sex, age, marital status, smoking status (current, former or never smoker), smoking pack-years, weight change, years of university, TV hours/day, family history of T2D, physical activity (MET-h/week), Trichopoulou’s 9-point score/Mediterranean dietary pattern, energy intake (kcal/day), sugar-sweetened beverage consumption (servings/day), snacking, following a special diet, prevalent hypertension, prevalent cancer, prevalent hypercholesterolemia, prevalent hypertriglyceridemia and obesity (>= 30 kg/m² yes, no)