Comment on: Davidson et al. High-Dose Vitamin D Supplementation in People With Prediabetes and Hypovitaminosis D. Diabetes Care 2013;36:260–266

We have read with interest the work by Davidson et al. (1) reporting in this journal that in a non-Caucasian population with impaired fasting glycemia or impaired glucose tolerance and low vitamin D levels, vitamin D supplementation had no effect on estimates of insulin secretion, insulin sensitivity, or incident diabetes.Our research group started a similar study (ClinicalTrials.gov number, NCT01183442) in Caucasians with postchallenge hyperglycemia (i.e., 2-h glucose ≥140 mg/dL), vitamin D deficiency, and coronary artery disease. As in the study by Davidson et al. (1) we had to prescreen a high number of patients ( n = 1,814). Five …