Originally from Sioux Falls, South Dakota, Dr. O'Day earned her medical degree from the University of Minnesota Medical School in the Twin Cities. She completed an internship and residency in internal medicine at Brigham and women's Hospital in Boston, and a fellowship in endocrinology, diabetes and metabolism at the New York University School of Medicine in New York. Dr. O'Day is board certified in internal medicine and endocrinology, diabetes and metabolism.

Dr. O'Day has a special interest in diabetes management, cystic fibrosis related diabetes, thyroid disorders, thyroid cancer, pituitary disorders, polycystic ovarian syndrome, osteoporosis and adrenal disorders. Prior to relocating to Denver, Dr. O'Day was working as an endocrinologist in Minnesota, in the Twin Cities area.

Dr. O'Day and her family moved from Minneapolis to Denver for the sunshine and the mountains. During her free time she enjoys hiking with her husband and son, and all things Disney.