BACKGROUND This study aimed to investigate the incidence of post-transplant diabetes mellitus (PTDM) in renal transplant (RT) patients at our center and to explore new risk factors for PTDM. MATERIAL AND METHODS This retrospective study included RT patients from 2010 to 2022. Clinic data on RT patients were obtained from hospital electronic medical records. CYP3A5*3, POR*28, ABCB1 (3435 C>T), and ABCB1 (1236 C>T) were genotyped in RT patients. The associations between age, BMI, concentration of tacrolimus (TAC), polymorphism of genes, antibiotics (eg, penicillins, cephalosporins, oxazolidinones, quinolones), numbers and days of antibiotic use, and PTDM were analyzed. RESULTS In this study, 409 patients with RT were included. The cumulative incidence of PTDM in the first year after RT was 9.05%. The numbers and days of antibiotic use in PTDM patients were significantly higher than those in non-PTDM patients. Multivariate logistic regression analysis identified age (OR=1.047, P=0.014), body mass index (BMI) (OR=1.178, P=0.007), dose-adjusted trough concentration of TAC (TAC C₀/D) at 7 days after RT (OR=1.159, P=0.042), trough concentration of TAC (TAC C₀) at 28 days after RT (OR=1.094, P=0.042), and levofloxacin (OR=5.975, P=0.003) as independent risk factors for PTDM. CONCLUSIONS In addition to age, BMI, and TAC concentration after RT, antibiotic use may be a novel factor affecting PTDM. The use of antibiotics may influence the development of PTDM.