Effect of 1-year oral cholecalciferol on a metabolic profile and blood pressure in poor-controlled type 2 diabetes mellitus: an open-label randomized controlled pilot study

Purpose Hypovitaminosis D has been associated with many cardio-metabolic disorders, although their pathogenetic link still remains unclear. Our aim was to evaluate whether 1-year vitamin D (D) supplementation could improve glycemic control, lipid profile, systolic (SBP) and diastolic (DBP) blood pressure levels and body composition. Methods In an open-label randomized-controlled pilot study, thirty poor-controlled (HbA1c > 59 mmol/mol) type 2 diabetic patients (age 71.5 +/- 3.2 years, M/F 21/9, BMI 29.8 +/- 3.6 kg/m(2)) with hypovitaminosis D (25OHD 22.0 +/- 11.3 nmol/l) were randomized to cholecalciferol supplementation (500 UI/kg p.o. weekly, + D) or observation (- D) for one year. Changes in parameters of glucose, lipid and blood pressure control at 3, 6, 9 and 12 months vs. baseline were assessed. Results One-year D supplementation restored D status and had a beneficial effect on fasting glucose (FG, mean percentage changes +/- SD, - 1.8% +/- 23.1 vs. + 18.8% +/- 30.0), glycosylated haemoglobin (HbA1c, - 13.7% +/- 14.5 vs. - 4.2% +/- 14.1), SBP (- 13.4% +/- 8.5 vs. - 2.4% +/- 12.6) and HDL-cholesterol levels (- 2.1% +/- 14.0 vs. - 10.9% +/- 12.9;p < 0.05 for all comparisons) in + D vs. - D patients, respectively. In the former, a reduction in HBA1c, SBP and DBP levels, BMI, fat mass index (FMI) and ratio (FMR) was observed after 1 year (p < 0.05 for all comparisons vs. baseline). We noticed a relationship between 1-year mean percentage changes of serum 25OHD and SBP levels (R = - 0.36,p < 0.05). Conclusion One-year cholecalciferol supplementation, able to restore D status, significantly improves FG, HbA1c, SBP and HDL-cholesterol levels in patients with poor-controlled type 2 diabetes mellitus and D deficiency.