Impact of diabetes mellitus on recurrence and progression in patients with non-muscle invasive bladder carcinoma: a retrospective cohort study

Objective: The aim of the present study was to investigate the relationship between diabetes mellitus (DM) and tumor features in patients with non‐muscle invasive bladder cancer (NMIBC). Methods: Data from 251 patients who underwent transurethral resection (TUR) for NMIBC from January 2000 to June 2010 were analyzed retrospectively. Patients were divided into two groups: Group I, 159 patients (63%) who did not have DM at the time of surgery; and (ii) Group II, 92 patients (37%) who had DM at the time of surgery. Recurrence‐ and progression‐free survival was assessed in both groups. Preoperative HbA1c levels, as parameter of glycemic control, were determined in Group II patients, with patients divided into two subgroups: (i) HbA1c ≥7.0%; and (ii) HbA1c <7.0%. The clinical features of the bladder tumor were compared in these two subgroups. Results: Compared with Group I, Group II patients were older and had a higher rate of hypertension, recurrence, and progression (P < 0.05). Univariate survival analysis showed that gender, DM, smoking, and serum creatinine were associated with recurrence‐free survival (P < 0.05), whereas DM, stage, grade, intravesical instillation, and serum creatinine were associated with progression‐free survival. In multivariate survival analysis, DM was found to be an independent factor for recurrence‐ (hazard ratio [HR] 2.11; 95% confidence interval [CI] 1.4–3.2; P = 0.001) and progression‐free survival (HR 9.35; 95% CI 3.1–28.6; P = 0.001). Furthermore, patients with HbA1c ≥7.0% exhibited a significantly higher rate of multiplicity (P = 0.001), tumor grade (P = 0.03), and intravesical treatment (P = 0.04). Conclusions: In conclusion, DM seems to be an independent predictor of recurrence‐ and progression‐free survival in NMIBC patients. Further prospective studies are needed to establish the prognostic significance of postoperative glycemic control in this patient population.