BackgroundHyperglycemia is associated with series of process leading to oncogenesis. Evidence has shown that diabetes mellitus (DM) seems to be associated with poor prognosis in patients with bladder cancer. However, evidence on the effect of glycemic control on the outcomes of bladder cancer is still limited. In the current study, we aimed to investigate the effect of DM and glycemic control on the prognosis of bladder cancer.MethodsWe conducted a retrospective chart review of a prospective database from January 2012 to December 2017. Patients with newly diagnosed non-muscle invasive bladder cancer (NMIBC) were included. They were classified into the DM and non-DM groups. Prognosis including recurrence rate, progression rate, recurrence-free survival (RFS), and progression-free survival was compared between the two groups. Subgroup analysis of the DM subgroup, in which patients were classified by HbA1C level, was conducted to investigate the effect of glycemic control.ResultsA total of 287 patients were included in our study, with 61 patients in the DM group and 226 patients in the non-DM group. No statistically significant difference was found in the prognosis between the DM and non-DM groups. Subgroup analysis revealed higher recurrence rate (P = 0.037) and worse RFS (log-rank P = 0.019) in patients with HbA1C ≥ 7.ConclusionsDM is not a risk factor for recurrence and progression in patients with NMIBC. However, poor glycemic control is associated with poor prognosis in patients with both DM and NMIBC. Further prospective studies are needed to confirm current results.