Bidirectional association between type 2 diabetes and irritable bowel syndrome: A large-scale prospective cohort study

Aim: To examine the bidirectional association between type 2 diabetes (T2D) and irritable bowel syndrome (IBS) in a large prospective population cohort. Methods: Participants free of IBS at baseline in the UK Biobank were included in the analysis of T2D and incident IBS (cohort 1), with 11 140 T2D patients and 413 979 non-T2D patients. Similarly, those free of T2D at baseline were included in the analysis of IBS and incident T2D (cohort 2), with 21 944 IBS patients and 413 979 non-IBS patients. Diagnoses of T2D and IBS were based on International Classification of Disease-10 codes. The Cox proportional hazards model was used to estimate adjusted hazard ratios (HRs). Results: In cohort 1, 8984 IBS cases were identified during a median 14.5-year follow-up. Compared with non-T2D, T2D patients had a 39.0% increased risk of incident IBS (HR = 1.39, 95% confidence interval [CI]: 1.23-1.56, P < .001), with a higher IBS risk in those with higher fasting blood glucose levels (HR = 1.43, 95% CI: 1.19-1.72, P < .001) or longer T2D duration (HR = 1.47, 95% CI: 1.23-1.74, P < .001). In cohort 2, 29 563 incident T2D cases were identified. IBS patients had an 18.0% higher risk of developing T2D versus non-IBS patients (HR = 1.18, 95% CI: 1.12-1.24, P < .001). A similar excess T2D risk was observed in IBS patients with a duration of either less than 10 years, or of 10 years or longer. Further sensitivity analysis and subgroup analysis indicated consistent findings. Conclusions: T2D and IBS exhibit a bidirectional association, with an increased risk of co-morbidity. Awareness of this association may improve the prevention and management of both diseases.