Role of Empirical Treatment with Vitamin D in Improving Glycemic Control of Type 2 Diabetes Mellitus Patients

Background: Type 2 Diabetes Mellitus (T2DM) remains a global health challenge, with many patients failing to achieve optimal glycemic control. Vitamin D, through its effects on insulin secretion and sensitivity, has emerged as a potential adjunctive therapy. However, evidence from clinical trials on its efficacy has been inconsistent. Objective: To evaluate the efficacy of empirical vitamin D supplementation as an adjunct therapy in improving glycemic control in patients with T2DM. Methods: A randomized, double-blind, placebo-controlled trial was conducted over 24 weeks. Sixty patients with T2DM (HbA1c >6.5%) were randomized into two groups. The intervention group (n=30) received oral Vitamin D₃ (20,000 IU weekly for 8 weeks, then 1,000 IU daily for 4 weeks) alongside standard anti-diabetic therapy. The control group (n=30) received an identical placebo with standard therapy. The primary outcome was the change in HbA1c from baseline to 12 weeks. Results: At baseline, both groups were well-matched in clinical parameters, including mean HbA1c (Vitamin D: 9.51%; Placebo: 9.55%). After 12 weeks, the Vitamin D group exhibited a significantly greater reduction in HbA1c compared to the placebo group (mean post-treatment HbA1c: 7.81% vs. 8.57%; mean difference: -0.76%, 95% CI: -1.13 to -0.39, p<0.001). Stratified analysis revealed the most pronounced benefits in females, patients aged ≥60 years, obese individuals, and those on insulin-only or oral anti-diabetic regimens. Conclusion: Empirical vitamin D supplementation significantly improves glycemic control in patients with T2DM, leading to a clinically meaningful reduction in HbA1c. The therapy was particularly effective in specific high-risk subgroups. These findings support the role of vitamin D as a safe and effective adjunctive treatment in T2DM management, warranting routine screening for deficiency in these populations.