eng Oriental Scientific Publishing Company Biomedical and Pharmacology Journal 0974-6242 2021-03-30 14 1 303 309 10.13005/bpj/2126 37021 article Mostafa Hassan Ragab 1 Eman Monir Sherif 2 Nadia Badawy Abd- El Gawad 3 Safaa Mohamed Elserougy 3 Eman Essam Shaban 4 Elham Mohamed Mostafa 4 Diabetes is one of the commonest chronic diseases worldwide. Vitamin D deficiency showed to be increasing, and have a potential role in autoimmune diseases among which in type 1 diabetes. The aim The aim of the study was to assess the impact of oral vitamin D supplementation on blood glucose (HbA1C) in T1DM patients and to find out the role of vitamin D as a biomarker for follow of T1DM patients compared to HbA1C. Subjects and methods: A randomized interventional clinical study was designed. The study enrolled 60 children patients with T1DM. Only 45 children continued to the end of study. Initial (pre-intake) assessment included history taking, clinical examination, and measurement of serum 25-OH vitamin D3 and serum HbA1C. These children received oral vitamin D supplements for 3 months then post-intake assessment were done again. Results: The study showed that serum vitamin D was deficient among Egyptian children and adolescents with T1DM (mean 11.4±3.4 ng/ml). , 53.33% of the patients had vitamin D deficiency with a 35.6% had insufficiency and 11.11% were VD sufficient.   Patients received oral vitamin D supplementation for 3 months after which marked improvement in the levels of serum vitamin D levels and HA1C, 87.5% and 86.5% respectively. https://biomedpharmajournal.org/vol14no1/influence-of-supplementary-vitamin-d-on-the-prognostic-pathway-of-type1-diabetes-among-children/ Diabetes - Type1 diabetes mellitus (T1DM) -Vitamin D -Ultra-Violet Index