OBJECTIVE:To assess rates of, and factors associated with, trial of labor and vaginal delivery among pregnancies complicated by both gestational diabetes (GDM) and a previous cesarean delivery. METHODS:In a retrospective study of singleton deliveries at a university hospital in Israel between 2009 and 2015, women with one previous cesarean delivery and GDM were matched to those without GDM by past cesarean delivery indication: non-favorable (non-progressive labor or failed induction) or favorable (all other indications). Computerized files were reviewed, and maternal, obstetric, and neonatal outcomes were compared. RESULTS:In total, 109 women with GDM were matched to 109 control women. Trial of labor was attempted by 55 (50.5%) women in the control group and 11 (10.1%) in the GDM group (P<0.001). Overall, 42 (38.5%) control women and 5 (4.6%) women with GDM delivered vaginally (P<0.001). Multivariable logistic regression identified lack of GDM as the most significant factor associated with trial of vaginal delivery, followed by a prior vaginal delivery. Among women attempting a trial of labor, past vaginal delivery, but not GDM status, was associated with successful vaginal delivery. CONCLUSION:GDM significantly diminished the likelihood of a trial of vaginal delivery after cesarean delivery and its subsequent success.