Aretaeus was a Greek physician from Cappadocia in Asia Minor who practiced medicine during the Roman Empire in the 2nd century CE. The exact dates of his life are uncertain, but many scholars place him in this period, possibly as a contemporary of the famous doctor Galen. Little is known about his personal life or education. He was a member of the Pneumatist school of medicine, which considered pneuma (breath or spirit) a vital force for health, and he was also a dedicated follower of the older Hippocratic tradition.

His surviving works are eight books of medical treatises, written in an archaic Greek dialect to honor Hippocrates. They are organized into four main texts: On the Causes and Symptoms of Acute Diseases, On the Causes and Symptoms of Chronic Diseases, On the Therapy of Acute Diseases, and On the Therapy of Chronic Diseases. These works provide the primary evidence for his ideas and practice.

Aretaeus is historically important for his exceptionally clear and compassionate clinical descriptions of diseases. According to modern scholars, he left classic accounts of asthma, epilepsy, and pneumonia. He is most famous for providing the first detailed description of the symptoms of diabetes, a name he coined. Although not widely cited in his own time, his writings were rediscovered in the 16th century and have since been praised for their observational skill and literary quality, offering a valuable window into Roman-era medical theory and practice.