Abstract. Background: to evaluate the effects of Vitamin D3 on glyco-metabolic control in type 2 diabetic patients with Vitamin D deficiency. Methods: one hundred and seventeen patients were randomized to placebo and 122 patients to Vitamin D3. We evaluated anthropometric parameters, glyco-metabolic control, and parathormone (PTH) value at baseline, after 3, and 6 months. Results: a significant reduction of fasting, and post-prandial glucose was recorded in Vitamin D3 group after 6 months. A significant HbA1c decrease was observed in Vitamin D3 (from 7.6% or 60 mmol/mol to 7.1% or 54 mmol) at 6 months compared to baseline, and to placebo (p < 0.05 for both). At the end of the study period, we noticed a change in the amount in doses of oral or subcutaneous hypoglycemic agents and insulin, respectively. The use of metformin, acarbose, and pioglitazone was significantly lower (p = 0.037, p = 0.048, and p = 0.042, respectively) than at the beginning of the study in the Vitamin D3 therapy group. The units of Lispro, Aspart, and Glargine insulin were lower in the Vitamin D3 group at the end of the study (p = 0.031, p = 0.037, and p = 0.035, respectively) than in the placebo group. Conclusions: in type 2 diabetic patients with Vitamin D deficiency, the restoration of value in the Vitamin D standard has led not only to an improvement in the glyco-metabolic compensation, but also to a reduced posology of some oral hypoglycemic agents and some types of insulin used.
