The study aimed to investigate whether the glucose level improves and what factors affect the improvement in glucose control after the eradication of hepatitis C virus (HCV). A total of 1090 patients with HCV infections were enrolled, among which 278 (25.5%) patients were diagnosed with prediabetes, and 89 (8.16%) patients were diagnosed with diabetes. In the cohort, 990 patients belonged to sustained virological response (SVR) group and 100 belonged to non-SVR group. Decreases in the fasting plasma glucose (FPG) level were found in the SVR group but not in the non-SVR group (p < 0.001; p = 0.267). In the SVR group, subjects with baseline FPG ≥ 5.6 mmol/L were further stratified into glycometabolism-improved (N = 182) and unimproved (N = 150) groups according to their FPG after viral eradication. Multivariate analysis showed that older age, higher baseline HCV RNA, glucose, total bilirubin and alanine aminotransferase levels were independent risk factors for insufficient glucose improvement. In conclusion, patients with HCV infection had a higher prevalence of abnormal glycometabolism. It could be improved after viral eradication, indicating that HCV may influence glycometabolism. Moreover, Age, baseline HCV RNA, glucose, total bilirubin and alanine aminotransferase levels were impact factor for glycometabolism improvement after viral eradication.