Background Pancreatic cancer (PC) is among the most deadly forms of cancer; however, the risk factors of PC have yet to be sufficiently identified. In the present study, we sought to screen all prior diseases associated with PC incidence concurrently and construct pathways for the diseases. Materials and methods This total population-based case–control study used data collected from Taiwan's National Health Insurance Research Database for the period covering 1997–2013. The case group included 3726 patients newly diagnosed with PC, who were precisely matched to 3726 controls based on gender, age, residence, and insurance premiums. Stepwise multivariate logistic regression was used to screen previous diseases in windows of 1, 2 …, 9 years prior to the first diagnosis of PC. Path analysis was used to construct the pathways between relevant prior diseases and PC. Results Within 1 year prior to PC diagnosis, a total of 11 diseases were significantly correlated with PC, included 9 positive and 2 negative associations. Path analysis identified diabetes, pancreatitis as diseases with direct positive pathways to PC incidence, and dementia with direct negative pathways. Conclusions It appears that diabetes, peptic ulcer, and digestive conditions were the prior diseases associated with PC incidence.