Dr. Harstine was born in Tulsa, Oklahoma. She received a BS degree from Phillips University. She earned her medical degree from the University of Kansas School of Medicine in 1976. She completed a residency at the University of Kansas School of Medicine - Wichita. She then completed a fellowship in diabetes at the Joslin Clinic in Boston and a fellowship in endocrinology at the Medical University of South Carolina.
She is board certified in both internal medicine and endocrinology. She has additional certifications in bone densitometry. Dr. Harstine has broad expertise in endocrinology including diabetes, thyroid disease, radioactive iodine therapy in hyperthyroidism and osteoporosis. She is a fellow of the American College of Endocrinology. She also holds membership in the American Society of Transplantation and the American Diabetes Association.