Objective: To compare the sensitivity and specificity of blood glucose and glycosylated hemoglobin in the diagnosis of diabetes. Methods: We selected 98 specimens from suspected diabetes patients who visited the Third People"s Hospital of Sanmenxia City from December 2022 to November 2024. Fasting plasma glucose (FPG), 2-hour postprandial glucose (2hPG), and glycated hemoglobin (HbA1c) were measured, and compared with the blood glucose levels of 90 individuals who underwent health check-ups at the same hospital. This was done to evaluate the accuracy of different diagnostic methods. Results: The research results showed that there were 80 confirmed positive cases and 4 negative cases of blood glucose testing; 87 cases were positive and 8 cases were negative in glycated hemoglobin testing, and its diagnostic efficacy was significantly better than that of blood glucose testing. The sensitivity, specificity, and overall diagnostic accuracy were all significantly improved, and the difference was statistically significant (P<0.05). All indicators of blood glucose in the observation group were higher than those in the control group, with P<0.05.Conclusion: HbA1c has high sensitivity and specificity in the diagnosis of diabetes, and can be used as the first screening index; The combination of FPG and 2hPG can further improve the detection rate and is recommended for frontline clinical screening.