Women with gestational diabetes mellitus (GDM) and obesity experience lower rates of breastfeeding. Little is known about breastfeeding among mothers with type 2 diabetes. Australian Indigenous women have a high prevalence of type 2 diabetes in pregnancy. We aimed to evaluate the association of hyperglycaemia, including type 2 diabetes, with breastfeeding outcomes.Indigenous (n = 495) and non-Indigenous (n = 555) participants of the Pregnancy And Neonatal Diabetes Outcomes in Remote Australia (PANDORA) cohort included women without hyperglycaemia in pregnancy (n = 222), with GDM (n = 684) and with type 2 diabetes (n = 144). The associations of hyperglycaemia in pregnancy and breastfeeding at hospital discharge, 6 weeks and 6 months post-partum were evaluated with logistic regression, after adjustment for maternal obesity, ethnicity, maternal and neonatal characteristics.Indigenous women were more likely to predominantly breastfeed at 6 weeks across all levels of hyperglycaemia. Compared with women with no hyperglycaemia in pregnancy, women with type 2 diabetes had lower odds for exclusive breastfeeding at discharge (adjusted OR for exclusive breastfeeding 0.4 [95% CI 0.2, 0.8] p = 0.006). At 6 weeks and 6 months, the relationship between type 2 diabetes and predominant breastfeeding was not statistically significant (6 weeks 0.7 [0.3, 1.6] p = 0.40, 6 months 0.8 [0.4, 1.6] p = 0.60). Women with gestational diabetes were as likely to achieve predominant breastfeeding at 6 weeks and 6 months as women without hyperglycaemia in pregnancy.Indigenous women had high rates of breastfeeding. Women with type 2 diabetes had difficulty establishing exclusive breastfeeding at hospital discharge. Further research is needed to assess the impact on long-term breastfeeding outcomes. Graphical abstract.