He is known for his co-discovery of glycated hemoglobin or A1C, a major diagnostic indicator of pre-diabetes and diabetes.
He received the AB degree from Harvard in 1957 majoring in chemistry and the MD from the University of Pennsylvania School of Medicine in 1961.
After a medical residency at New York Hospital, he completed a fellowship in hematology at the Thorndike Laboratory under mentorship of James Jandl.
From 1991 until 1998, he directed the Harvard-Markey Program in Biomedical Sciences, which provides graduate students an added year of training in human biology and disease pathophysiology.
[3] His major work included The second 20 years of Bunn's research focused on identification of domains on erythropoietin (EPO) that bind to its receptor, and on characterizing the oxygen-dependent degradation domain of the HIFa transcription factor responsible for hypoxic induction of EPO and other physiologically relevant proteins.