Pancreatic cancer is a type of highly malignant digestive system tumor, with a 5-year overall survival rate of < 10%. In recent years, a large number of studies have shown that there is a two-way relationship between pancreatic cancer and diabetes; diabetes is not only one of the high-risk factors for pancreatic cancer, but also a paraneoplastic phenomenon caused by pancreatic cancer. Hyperglycemia and hyperinsulinemia in patients with type 2 diabetes are risk factors for pancreatic cancer, and on the contrary, pancreatic cancer cells cause the dysfunction of pancreatic β cells through autocrine or paracrine pathways and thus lead to the onset of pancreatic diabetes. This article reviews the epidemiology and pathogenesis of pancreatic cancer and the two-way relationship between pancreatic cancer and diabetes, so as to provide a reference for clinical practice.