Background: Diabetes mellitus (DM) is recognized as a risk factor for pancreatic cancer and expected to be a clue for early diagnosis. However, it is still obscure whether a diagnostic strategy using DM as a clue can detect early pancreatic cancer or not Methods: We retrospectively reviewed the records of consecutive 150 patients with pancreatic cancer, and investigated the stage with regard to the reasons for diagnosis. We compared patients diagnosed by imaging studies performed in groups that DM were newly diagnosed, longstanding, and not accompanied. Results: The prevalence of DM in patients with pancreatic cancer was 41% (62/150). The disease stages consisted of IA (5%), IB (14%), IIA (2%), IIB (4%), III (24%), and IV (51%). Forty percents (25/62) of DM in pancreatic cancer patients was new-onset (< 2 years in duration). Sixteen patients (11%) were asymptomatic at diagnosis of pancreatic cancer. The disease stage did not differ among patients with new-onset DM (< 2 years in duration), those with longstanding DM (> 2 years in duration), and those without DM. In asymptomatic patients, the prevalence of stage I patients was high as 32%, but it was not statistically signifi cant. The majority (88%) of pancreatic cancer patients with new-onset DM had symptoms. Conclusions: Diabetes is very common (41%) in pancreatic cancer. Our analysis did not reveal that pancreatic cancer patients diagnosed in association with new-onset DM had lower disease stage than longstanding DM or non-DM patients.