This study was a cross-sectional, observational design without involving random grouping or intervention. From July 2026 to June 2027, 199 children with type 1 diabetes who had received insulin treatment for at least 6 months and their main family caregivers were recruited by a continuous enrollment method from the endocrinology department of a tertiary children's hospital in Zhejiang Province. Qualified investigators conducted on-site distribution and collection of structured questionnaires, collecting general information of the children, the occurrence of skin complications, and the insulin injection behaviors of the caregivers. At the same time, personnel with ultrasound qualifications used a wireless handheld ultrasound combined with a skin lipid caliper to uniformly measure the subcutaneous fat thickness at 8 sites including the abdomen, buttocks, arms, and thighs.