A multi-state analysis of disease trajectories and mental health transitions in patients with type 2 diabetes: A population-based retrospective cohort study utilizing health administrative data

Aims: To investigate the risk of major depression and dementia in patients with type 2 diabetes, including dementia resulting from depression, and their impact on diabetes-related complications and mortality. Methods: We conducted a population-based retrospective cohort study including 11,441 incident cases of diabetes in 2015–2017, with follow-up until 2022. A multi-state survival analysis was performed on a seven-state model with 15 transitions to capture disease progression and onset of mental disorders. Results: Eight-year probabilities of depression, dementia, diabetes-related complications, and death were 9.7% (95% CI 8.7–10.7), 0.9% (95% CI 0.5–1.3), 10.4% (95% CI 9.5–11.4), and 14.8% (95% CI 13.9–15.7), respectively. Depression increased the risk of dementia up to 3.7% (95% CI 2.0–5.4), and up to 10.3% (95% CI 0.3–20.4) if coupled with diabetes complications. Eight-year mortality was 37.5% (95% CI 33.1–42.0) after depression, 74.1% (95% CI 63.7–84.5) after depression plus complications, 76.4% (95% CI 68.8–83.9) after dementia, and 98.6% (95% CI 96.1–100.0) after dementia plus complications. Conclusions: The interconnections observed across depression, dementia, complications, and mortality underscore the necessity for comprehensive and integrated approaches in managing diabetes. Early screening for depression, followed by timely and targeted interventions, may mitigate the risk of dementia and improve diabetes prognosis.