Diabetes Trajectory and Pancreatic Cancer Detection in Patients with Diabetes: A Nationwide Survey Through Japan Diabetes Society-Certified Facilities

Background/Objectives: Diabetes mellitus (DM) and pancreatic cancer (PC) have a bidirectional relationship. Although new-onset DM (NODM) is recognized as a potential clue to PC, worsening glycemic control in long-standing DM (LSDM) may also precede PC diagnosis. We aimed to characterize patterns of PC detection in specialist diabetes practice and to examine the association between diabetes-related diagnostic triggers and stage at diagnosis. Methods: This retrospective, nationwide, two-stage survey included patients with PC and DM treated at Japan Diabetes Society-certified educational facilities between 2017 and 2021. NODM and LSDM were defined as diabetes diagnosed within and more than 3 years before PC diagnosis, respectively. Results: Among 2291 patients with PC, 549 (24.0%) had NODM and 1742 (76.0%) had LSDM. Compared with symptom-based diagnosis, diabetes-related detection was associated with a higher proportion of stage 0/IA disease (11.0% vs. 3.9%) and a lower proportion of stage IV disease (26.1% vs. 49.5%). Diabetes-related detection was independently associated with stage 0/IA disease, with an adjusted odds ratio of 2.87 (95% confidence interval, 1.72–4.81; p < 0.001). Among patients with worsening LSDM, 57.2% were diagnosed with PC within 3 months and 79.4% within 6 months. Among those with available longitudinal body-weight data, 66.9% experienced weight loss of at least 2.5% compared with 1 year before PC diagnosis. Conclusions: Potential clues to PC in diabetes practice extend beyond NODM to deterioration of pre-existing diabetes, with weight loss frequently observed among patients with available longitudinal data. Prospective studies with appropriate control groups are needed to determine which diabetes trajectories can reliably identify patients who warrant targeted pancreatic evaluation.