Backgrounds: The understanding of the efects and role of vitamin D and its analogues in the functioning of body tissues, systems and organs has improved substantially over the last decade. The potential extra-skeletal role of vitamin D has been a rich area of interest and research over the last decade. Vitamin D deficiency has been implicated in a variety of chronic diseases, including bone mineral disease, autoimmunity, cancer, and diabetes. For years, interest in diabetes mellitus and vitamin D metabolism has grown. Many epidemiological studies have found high prevalence of vitamin D defciency in children with type 1 diabetes mellitus, suggesting a strong relationship between the two.
Objective: Aims of this study were to measure 25 hydroxy vitamin D (25 OHD) level in type 1 diabetes mellitus and to compare them with 25 hydroxy vitamin D (25 OHD) levels in non- diabetic subjects at the same period.
Methods: A cross sectional study was carried out between 2018 - 2019. This study including 40 patients with type 1 diabetes mellitus at Saiful Anwar Hospital, Malang, Jawa Timur and 40 children non - diabetic control children. Clinical data 25OHD serum level were collected and measured with Enzyme-linked Immuno Assay (ELISA) method. A serum plasma 25(OH)D concentration of <20 ng/ml was considered as deficiency, a concentration between 21 and 29 ng/ml as insufficiency, and a plasma concentration above 30 ng/ml as normal (sufficient).
Results: The mean serum 25OHD in type 1 diabetes mellitus children was 9.35 ± 5.28 ng/ml (range 1.07 – 26.64 ng/ml) and in the controls was 9.46 ± 4.07 ng/ml (range 2.86 – 20.3 ng/ml). The mean serum 25OHD in type 1 diabetes mellitus children was lower than that of controls (P = 0.69). All participants (type 1 diabetes mellitus patients and controls) had inadequate levels of vitamin D. 
Conclusion: Children with T1DM have lower vitamin D levels than control group.