Aim: Pancreatic cancer (PC) is a disease with complex and poorly understood etiology. One of the common risk factors of PC is diabetes mellitus (DM). Increased carbohydrate antigen (CA) 19-9 levels can be used as a biomarker in diagnosis of PC. However, CA 19-9 levels have been reported to increase in some benign conditions as well. Increased levels of such PC-associated biomarkers due to benign conditions can lead to unnecessary interventional procedures. The aim of this study was to question the need for a new CA 19-9 cut-off value when diagnosing PC in patients with type II DM.

Material and Methods: This retrospective study evaluated a total of 449 patients. The patients were divided into two groups: the normal glucose regulation (NGR) group (n=292) and type II DM group (n=157). The mean glucose, HbA1c, CA 19-9, insulin, and homeostatic model assessment for insulin resistance (HOMA-IR) levels of the groups were compared. The correlation between CA 19-9 and glucose, HbA1c, insulin and HOMA-IR was evaluated.

Results: The type II DM group had significantly higher CA 19-9, glucose, HbA1c, insulin, as well as HOMA-IR levels compared to the NGR group (P=0.001 for CA 19-9 and P<0.001 in all other pairwise comparisons). There was a positive correlation between CA 19-9 and HbA1c as well as HOMA-IR (r=0.132, P=0.005; r=0.109, P=0.020, respectively).

Conclusion: A higher CA 19-9 cut-off value is needed when diagnosing malignant disease of the pancreas in patients with type II DM to prevent unnecessary invasive/noninvasive interventions.