Appendectomy and Subsequent Type 2 Diabetes – A National Cohort study

Background Acute appendicitis commonly necessitates surgical removal of the appendix which can cause a perturbation of the gut microbiota altering metabolic homeostasis. Previous studies have suggested a possible increased risk of developing type 2 diabetes (T2D) after appendectomy, although findings have been inconsistent. We aimed to evaluate whether appendectomy increased the incidence of T2D in a nationwide cohort. Materials and Methods In this register-based cohort study, all Danish citizens between 1995 and 2022 were included. Appendectomy cases were identified using national procedural codes in the Danish National Patient Register. Each patient subjected to appendectomy was matched 1:10 by age and sex. Incident T2D was ascertained via diagnosis codes and diabetes-specific prescription data. Cox proportional hazards models adjusted for demographic variables, socioeconomic factors, and comorbidity were employed to estimate hazard ratios (HR) for development of T2D following appendectomy. Analyses were stratified by age, sex, and calendar period with sensitivity analyses for appendicitis complexity and lag periods. Results Among 7,682,475 individuals, 176,984 (2.30%) underwent appendectomy. During 24 million person-years of follow-up, 56,276 individuals developed T2D (incidence rate: 2.3/1000 person-years). Appendectomy was associated with a slightly increased risk of T2D (adjusted HR 1.011; 95% CI 1.005–1.016), particularly in females (aHR 1.019; 95% CI 1.012–1.026) and those aged >40 y (aHR 1.028–1.042). Conclusions Appendectomy is associated with a marginal increase in T2D risk, most evident in older patients and females. These findings suggest potential metabolic consequences of appendectomy, but the modest effect size limits clinical implications regarding surgical decision-making in appendicitis.