Objective: To evaluate separate and combined contributions of gestational diabetes mellitus (GDM) and large-for-gestational age (LGA) on delivery outcomes. Methods: In a retrospective cohort study of term singleton deliveries between 2007 and 2014 in Tel Aviv, Israel, outcomes were compared between non-GDM/AGA pregnancies (reference) and three study groups: non-GDM/LGA, GDM/appropriate for gestational age (AGA) and GDM/LGA. Results: Overall, there were 62102 deliveries, of which 53201 (85.7%) were eligible for inclusion. Of these, 43775 (82.3%) were non-GDM/AGA, 6441 (12.1%) non-GDM/LGA, 2351 (4.4%) GDM/AGA, and 634 (1.2%) GDM/LGA. Compared with the reference group, the study groups had higher mean maternal age and higher rates of previous cesarean delivery, polyhydramnios, induction of labor, and cesarean delivery. Considering only women attempting vaginal delivery, the three groups were independently associated with adverse outcomes including cesarean delivery (adjusted odds ratio [aOR], 1.5, 1.6, and 2.6 for non-GDM/LGA, GDM/AGA, and GDM/LGA, respectively), mainly for prolonged first stage of labor, and hypoglycemia (aOR, 1.9, 2.5, and 4.6, respectively). LGA with and without GDM was associated with shoulder dystocia (aOR, 14.5 and 6.9, respectively), prolonged second stage, and jaundice. Conclusion: GDM and LGA share similarities in pregnancy complications. The presence of both has a cumulative impact.