Impact of diabetes duration and chronic pancreatitis on the association between type 2 diabetes and pancreatic cancer risk

Aim: To examine the impact of diabetes duration, chronic pancreatitis and other factors on pancreatic cancer risk. Methods: This retrospective cohort study using the UK General Practice Research Database compared pancreatic cancer incidence and risk in patients with type 2 diabetes mellitus (T2DM) versus patients without diabetes. Multivariate Cox regression adjusting for age, sex, history of chronic pancreatitis, gallbladder disease, obesity, smoking and alcohol use and Charlson comorbidity index was used to estimate hazard ratio (HR) [95% confidence interval, CI]. Analyses were repeated using various time windows for diabetes duration. Results: A total of 1903 incident pancreatic cancers were identified, 436 in patients with T2DM (78.76 per 100 000 person-years [95% CI: 71.54, 86.51]) and 1467 in patients without diabetes (11.46 per 100 000 person-years [10.88, 12.06]). Pancreatic cancer risk was significant for T2DM (adjusted HR 1.80 [1.52, 2.14]), increasing age, history of chronic pancreatitis and tobacco use. For patients with chronic pancreatitis and T2DM, the adjusted HR was 12.12 [6.02, 24.40]. Incidence was highest in patients with >= 5 year duration of T2DM. In patient populations with duration of T2DM ranging from >= 1 to >= 5 years, adjusted HRs remained significant but point estimates attenuated slightly with longer duration of T2DM. Conclusions: Patients with T2DM had an 80% increased risk of pancreatic cancer versus patients without diabetes. Patients with T2DM and chronic pancreatitis were 12 times more likely to develop pancreatic cancer.