Objective To investigate the changes of bilirubin, alkaline phosphatase (ALP) and 25 hydroxyvitamin D in peripheral blood of children with type 1 diabetes (T1DM) and their correlation. Methods 105 children with T1DM who were treated in our hospital from January 2021 to December 2023 were selected as the observation group, while 100 healthy children who underwent physical examinations were selected as the control group. The differences in peripheral blood bilirubin, ALP and 25 hydroxyvitamin D between the two groups were compared, as well as the differences in peripheral blood bilirubin, ALP and 25 hydroxyvitamin between the observation group and children with different clinical characteristics. Results The total bilirubin, conjugated bilirubin, and non tuberculosis bilirubin in the peripheral blood of the observation group, respectively, were significantly higher than those in the control group (P＜0.05). There was no statistically significant difference in ALP between the observation group and the control group (P＞0.05). The 25 hydroxyvitamin D in the observation group, significantly was lower than that in the control group (P＜0.05). There was no statistically significant difference in the total bilirubin, conjugated bilirubin, and unconjugated bilirubin levels in the peripheral blood of children with different genders, ages, disease duration, and HbA1c levels in the observation group(P＞0.05) . The 25 hydroxyvitamin D of children with HbA1c≥ 10% in the observation group was significantly lower than that of children with HbA1c＜10% (P＜0.05). Conclusion The peripheral blood bilirubin of T1DM patients is significantly increased, and the 25 hydroxyvitamin D level is reduced. 25 hydroxyvitamin D may be related to HbA1c.