Excellent accuracy of glucose level in cystic fluid for diagnosis of pancreatic mucinous cysts

Background: CEA in pancreatic cystic fluid (PCF) is standard for mucinous cysts diagnosis. Glucose is an alternative, but its accuracy remains poorly described. Aims: To evaluate PCF glucose using a glucometer and compare its accuracy with CEA for mucinous cysts diagnosis. Materials and Methods: In frozen PCF obtained by EUS-FNA, glucose was evaluated using a glucometer. CEA and cytology were available as standard of care. The accuracy of glucose and CEA was calculated using receiver operator (ROC) curves. Definitive diagnoses were surgical or clinicopathological. Results: We evaluated 82 patients with a mean age of 61.3 ± 14.8 years (25–91), predominantly (59%) females. Diagnoses included 17 serous cystadenomas, five pseudocysts, 20 intraductal papillary mucinous neoplasms, three mucinous cystic neoplasms, five adenocarcinomas, four neuroendocrine tumors, two other types, 26 non-defined. The median glucose levels (interquartile range) were 19 mg/dL (19–19) in mucinous and 105 mg/dL (96–127) in non-mucinous cysts (p < 0.0001). The median CEA level was 741 ng/mL (165–28,567) in mucinous and 9 ng/mL (5–19) in non-mucinous cysts (p < 0.0001). For mucinous cyst diagnosis, a CEA > 192 ng/mL had a sensitivity of 72% (95% CI 51–88) and a specificity of 96% (95% CI 82–100), and ROC analysis showed an area under the curve (AUC) of 0.842 (95% CI 0.726–0.959), while glucose < 50 mg/dL had a sensitivity of 89% (95% CI 72–98), a specificity of 86% (95% CI 67–96), and an AUC of 0.86 (95% CI 0.748–0.973). Pseudocysts presented low glucose, identically to mucinous cysts, with CEA allowing differential diagnosis. Conclusion: Glucose measured by a glucometer is accurate for mucinous cyst diagnosis, with significantly higher levels in non-mucinous cysts, except pseudocysts.