Objective Acute pulmonary embolism (PE) is one of the main causes of death and has a course as massive (MPE) or non-massive (NMPE). The study investigates the indicator potential of Glucose to Potassium ratio (GPR) in the differential diagnosis of MPE and NMPE. Materials and Methods The study was designed as a retrospective cross-sectional clinical cohort in patients with PE. A total of 111 participants enrolled in the research separating two groups: MPE (n:54) and NMPE (n:67). The GPR was calculated by dividing serum glucose by potassium levels and its results were compared with D-Dimer, Pulmonary Artery Pressure (PAP), and C-Reactive Protein Test (CRP). Results D-Dimer was measured as 6.5 ± 5.7 µg/L in the MPE and found higher than the NMPE (3.9 ± 5.2 µg/L) (P = .019). CRP (100 ± 83.5 to 30.9 ± 42.7 mg/L; P = .0001) and PAP (49.5 ± 11.9 to 34.8 ± 7.3 mmHg; P = .0001) were found increased in the MPE. GPR strongly increased in the MPE (30.7 ± 7.5 to 24.9 ± 4.3; P = .0003) in line with CRP, D-Dimer and PAP. GPR showed a stronger diagnostic value (AUC: 0.733; P = .00001; Sensitivity:72%; Spesifity:70%; Cut-off: 26.5). PAP and GPR showed significant efficiency on occurrence of the MPE according to the binary logistic regression. Conclusion The GPR, as a novel and cheap marker, can be useful for diagnostic differentiation of MPE from NMPE, but weaker than PAP and better than D-dimer. Type of Study and Level of Evidence Level-II, Retrospective clinical cohort study.