A study of 25‑(OH)D₃ levels in children with type 1 diabetes mellitus and its influencing factors

The present study aimed to assess 25‑(OH)D3 levels, their influencing factors and their association in children with type 1 diabetes mellitus (T1DM). The medical records of children with T1DM were retrospectively collected from the Department of Endocrinology, Genetics and Metabolism, Shanxi Children's Hospital (Taiyuan, China), between January 2017 and December 2023, and designated as the T1DM group. The data of healthy children who underwent physical examinations as outpatients during the same period were collected and designated as the control group. Differences in 25‑(OH)D3 levels and the proportions of vitamin D deficiency and insufficiency between the two groups and among the subgroups [defined by age, sex, disease history, presence of diabetic ketoacidosis (DKA)/diabetic ketosis (DK), infection, and admission quarter] were analyzed, and the influencing factors were explored. The 25‑(OH)D₃ levels in the T1DM group and its various subgroups (classified by age, sex, and residence) were lower than those in the control group and the corresponding subgroups, whereas the proportions of vitamin D deficiency and insufficiency were higher. The 25‑(OH)D₃ level was negatively correlated with age. The 25(OH)D₃ levels and the proportions of vitamin D deficiency and insufficiency were significantly different among the T1DM subgroups, which were divided according to age, sex, whether newly diagnosed or complicated with DKA/DK or infection, and admission quarter Age, admission quarter, duration of disease, sex, place of residence and HbA₁C levels were identified as statistically significant factors affecting 25‑(OH)D₃ levels. In conclusion, insufficiency or deficiency of vitamin D during childhood may be an important factor in the occurrence of T1DM and its complications. The 25‑(OH)D₃ levels in the body are affected by several factors. Timely diagnosis and treatment of vitamin D deficiency in children may be helpful. However, due to the retrospective observational design of the present study and the absence of data on key confounders, prospective studies with standardized covariate collection are needed.