Clinical characteristics and individualized treatment strategies for children with type 1 diabetes and exogenous insulin antibody syndrome: a retrospective case series and literature review

Objective This study investigates the clinical characteristics, diagnostic strategies, and therapeutic outcomes of individualized treatment for children with type 1 diabetes mellitus (T1DM) complicated by exogenous insulin antibody syndrome (EIAS). Methods A retrospective case series study was conducted on five pediatric patients diagnosed with T1DM+EIAS at a single center between January 2016 and January 2026. Among 1,245 T1DM patients evaluated, 5 (0.4%) met EIAS diagnostic criteria. Data included demographics, clinical manifestations, laboratory findings (insulin antibodies [IA], C-peptide, continuous glucose monitoring [CGM]), treatment regimens, and outcomes. Longitudinal autoantibody profiles, thyroid function, immune parameters, and cytokines were assessed at four time points. A narrative review of published EIAS cases was conducted following PRISMA guidelines. Results Case 1 achieved glycemic stability using ultra-rapid insulin with closed-loop pump (6-hour active insulin duration). Case 2, a 1-year-old infant, required regular insulin every 4 hours (six doses daily). Case 3 switched from pump to conventional multiple daily injections (MDI) with 4–6 daily injections. Case 4 used 4–6 daily aspart doses plus once-daily glargine. All four achieved TIR >70%. Case 5, with refractory disease and IA titer of 33.40 COI, received mycophenolate mofetil (MMF) 600–1,000 mg/m²/day. After 3 months, TIR improved to >70%, TBR <5%, and IA titers decreased by >30%. MMF discontinuation resulted in rapid recurrence of instability within 4 weeks. Conclusion EIAS is a rare cause of severe glycemic dysregulation in pediatric T1DM. CGM metrics (TIR, TBR, CV) are essential for assessment, as HbA1c may not reflect glycemic variability. Individualized insulin optimization improves TIR in most patients. For refractory cases, MMF may offer a potential therapeutic option. Due to the observational nature, small sample size (n=5), absence of a control group, and lack of blinding, these findings should be considered hypothesis-generating. Causal inferences cannot be drawn, and the results require validation in prospective, multicenter, controlled studies.