Type 2 diabetes (T2D) and its complications disproportionally affect American Indian and Alaska Native (AI/AN) peoples. Prescribing decisions for anti-diabetic medications are complicated and require balancing medication benefits, costs and side effects. Little is known about trends in anti-diabetic medication use as well as acute diabetes complications among AI/AN adults. Here, we examined patterns and trends in anti-diabetic medication use and rates of hospital admissions or emergency department (ED) visits due to severe hypoglycaemia and hyperglycaemia among AI/AN adults with T2D. We conducted a retrospective analysis of Indian Health Service (IHS) Improving Health Care Delivery Data Project. A total of 39 183 AI/AN adults aged ≥18 years with T2D who used IHS or Tribal health services during any of the fiscal years (FYs) 2009-2013 were included. Utilization rates of each class of anti-diabetic medications and rates of severe hypoglycaemia and severe hyperglycaemia in emergency room and/or inpatient discharge diagnoses were calculated for each year. Longitudinal statistical models were fitted to examine time trends of anti-diabetic medication use and complications. During 2009-2013, use of metformin (56.0%-60.5%), insulin (31.4%-35.9%) and dipeptidyl peptidase-4 inhibitors (1.4%-9.0%) increased, whereas the use of sulfonylureas (40.3%-32.9%) and thiazolidinediones (TZDs, 31.6%-8.8%) decreased significantly. Trends in severe hypoglycaemia (1.6%-0.8%) and severe hyperglycaemia (2.0%-1.6%) declined gradually. There were significant changes in the utilization of different anti-diabetic medication classes during 2009-2013 among AI/AN adults with T2D. Concurrently, there were significant reductions in severe hypoglycaemia and severe hyperglycaemia.