Endocrine Abstracts

Background: Vitamin D deficiency is an important public health problem because of its great impact on bone metabolism and the possible implication in cardiovascular outcomes, diabetes, cancer and mortality. Cross-sectional studies have related vitamin D deficiency with the prevalence of diabetes but there are only a few prospective cohort studies on the incidence of type 2 diabetes.

Objective: To investigate the relationship between levels of 25-hydroxyvitamin D and the incidence of type 2 diabetes in a Spanish population.

Methods: We undertook a population-based prospective study in a population from southern Spain. The first phase of the study (1996–1998) included 1226 individuals. Of this original cohort, 988 persons were reassessed in 2002–2004 and 961 in 2005–2007. At the second evaluation, we measured 25-hydroxyvitamin D and intact parathyroid hormone (iPTH), glycosylated hemoglobin and did an oral glucose tolerance test (OGTT) to 855 subjects. For the incidence study we excluded 172 subjects with diagnosed diabetes. After 4 years of follow up, 412 subjects were re-evaluated in 2005–2007 with an OGTT and glycosylated hemoglobin. All the participants completed a clinical survey, underwent an anthropometric study and provided a venous blood.

Results: The incidence of diabetes in subjects with 25-hydroxyvitamin D levels ≤18.5 ng/ml (percentile 25) was 12.4 vs 4.7% in subjects with levels >18.5 ng/ml. The likelihood of having diabetes during the four years of follow-up was significantly lower in the subjects with higher levels of 25-hydroxyvitamin D (OR=0.17 (0.05–0.61)). None of the subjects with levels higher than 30 ng/ml developed diabetes.

Conclusion: In this prospective study, we found a significant inverse association between serum 25-hydroxyvitamin D levels and the risk for type 2 diabetes in a population from the south of Spain.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.