Relationship between diabetes mellitus and the risk of pancreatic cancer
Patients with pancreatic cancer (PaC) are typically not diagnosed until the disease is at a surgically unresectable advanced stage, making it one of the most lethal malignancies worldwide. Patients with diabetes mellitus (DM) a disease that is increasing in prevalence worldwide, are two to three times more likely to develop PaC. Here, we review the clinical links between DM and PaC and the biological mechanisms that may contribute to these links. In particular, we examine molecular pathways that potentially account for development of PaC in patients who have had DM for various amounts of time. In addition, we also briefly discuss the potential effects of other factors such as different anti diabetic medicines on PaC risk. Observational studies indicate that newly developed DM may be a manifestation of PaC and that the risk for this cancer is increased in long term cases. Notably, development of PaC may be inhibited by using anti diabetic medications, such as metformin. However, DM in long term patients is more likely to be managed with insulin therapy, which is associated with an increased risk for developing PaC. How incretin based drugs and thiazolidinediones impact the incidence of PaC remains unclear. Thus, further research is needed to elucidate these relationships and to determine the causality and impact of DM severity and disease duration as well as residual biases and misclassifications.