Introduction: Diabetes is common in Pakistan, with prevalence rates ranged from 7.6 -11%. Diabetics especially type 2 diabetes mellitus have a much higher odds of being vitamin d deficient.

Objective: To compare mean decrease in glycated hemoglobin in vitamin D supplementation with placebo in the treatment of type I diabetes mellitus

Methodology: This study design was randomized controlled trial carried out at the medicine department Lady Reading Hospital Peshawar for duration of six months after synopsis approval from July 2021 to December 2021. Sixty patients were included in our study. Patients in group A were subjected to routine diabetes therapy plus vitamin D supplementation in a dose of 600000 units per oral every two weeks for 3 months and patients in group B were subjected to only routine diabetes therapy. Data was entered and analyzed by statistical package for social sciences (SPSS) version 20.

Results: Base line HbA1C Level among Group A patients was analyzed as Mean was 9.27 and Std. Deviation was 1.58 whereas in group B subjects, the mean HbA1C Level was 9.28 and Std. Deviation was 1.59. Post HbA1C Level in Group A patients was analyzed as Mean was 7.29 and Std. Deviation was 1.40 whereas in group B subjects, the post mean HbA1C Level was 7.51 and Std. Deviation was 1.73

Conclusion: Our study concludes that supplementation of Vitamin D could improve Vitamin D level in blood but have no significant association with the reduction of  HbA1c level in patients with  Type II diabetes mellitus.

Keywords: Glycated hemoglobin; Vitamin D supplementation, Type II diabetes mellitus