A more precise identification of mucinous cysts will lower the likelihood of needless pancreatic surgery. Pancreatic cyst fluid (PCF) contains glucose and carcinoembryonic antigen (CEA), which serve as biomarkers to differentiate mucinous from non-mucinous pancreatic cystic neoplasms (PCNs). To evaluate the diagnostic accuracy of combined CEA and glucose levels in PCF for distinguishing mucinous from non-mucinous PCNs preoperatively. After receiving approval from the Institutional Ethical Committee of Indira Gandhi Institute of Medical Sciences, Patna, a cross-sectional validation research was carried out. All patients ≥18 years of age who had undergone pancreatic surgery or endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) for a pancreatic cystic lesion and for whom PCF was acquired were eligible for inclusion. Patients were excluded if there was no PCF available, if they had been diagnosed with an extrapancreatic illness (such as ampullary adenoma), or if they could not be excluded due to pancreatic cancer generated from PCN. Diagnoses were pathologically confirmed. We performed measurements for CEA and glucose in PCF. CEA and glucose were measured using an Architect i2000SR analyzer (Abbott, Lake County, IL) and AU 5800 Beckman Coulter (Brea, CA), respectively. Diagnostic accuracy was evaluated by receiver operator characteristic (ROC) curves. PCF was obtained from 100 patients, of whom 54 (54%) had mucinous PCN and 46 (46%) had non-mucinous PCN. When CEA (cut-off ≥ 151 ng/ml) and glucose levels (cut-off ≤ 50 mg/dL) were combined, the results showed 46% sensitivity and 92% specificity. However, when CEA (cut-off ≥ 17 ng/ml) or glucose testing (cut-off ≤ 50 mg/dL) was used separately, the results showed 82% sensitivity and 73% specificity. The combined CEA and glucose testing in PCF demonstrated high specificity and sensitivity for differentiating mucinous from non-mucinous PCNs, suggesting its potential utility in preoperative diagnosis.