Serum 25-hydroxyvitamin D and incidence of diabetes in elderly people: The PRO.V.A. study

Context: Increasing research has shown that low levels of serum 25-hydroxyvitamin (25OHD) predict the onset of diabetes, but no research is available on this issue in elderly people. Objective: Our objective was to examine whether low serum levels of 25OHD are associated with a higher risk of incident type 2 diabetes over a lengthy follow-up in a representative group of elderly people. Design and Setting: This was a population-based cohort study as part of the Progetto Veneto Anziani (Pro.V.A.) Study over a follow-up of 4.4 years in the general community. Participants: Participants included 2227 participants (1728 with follow-up visits and 499 died during the follow-up) over 65 years of age without diabetes at baseline, of 2352 initially included. Main Outcome Measure: The main outcome measure was incident diabetes. Results: There were no baseline differences in known factors for the onset of diabetes (body mass index, waist circumference, total cholesterol, renal function, and hemoglobin A1c levels) between the groups with different serum 25OHD levels (≤25, 25-50, 50-75, and ≥75 nmol/L). Over a 4.4-year follow-up, 291 individuals developed diabetes, with an incidence of 28 events per 1000 person-years. No significant difference in the incidence of diabetes emerged between the baseline 25OHD groups. Cox's regression analysis, adjusted for potential confounders, revealed no relationship between low vitamin D levels and incident diabetes during the follow-up (hazard ratio [HR] = 1.05, 95% confidence interval [CI] = 0.76-1.45, P = .77; HR = 1.44, 95% CI = 0.95-1.98, P = .12; and HR = 1.37, 95% CI = 0.87-2.16, P = .17 for those with 25OHD ≤25, 25-50, and 50-75 nmol/L, respectively). Conclusion: Baseline serum concentrations of 25OHD were not associated with the incidence of diabetes in community-dwelling elderly people over a follow-up of 4.4 years. Copyright © 2014 by the Endocrine Society.