Many people with type 1 diabetes endure regular finger-stick blood tests and insulin shots as they try to keep levels of blood glucose within the normal range. To help them avoid this routine and achieve better blood glucose control, scientists at Massachusetts General Hospital and Boston University are testing an artificial pancreas that regulates glucose continuously and automatically. Worn on a belt like a cell phone, the device takes glucose readings every five minutes from a tiny sensor inserted about an eighth of an inch under the skin. It then administers precise doses of insulin and another important hormone, glucagon, to match physiological demands. In a small clinical trial led by HMS Instructor in Medicine Steven Russell, the re-invented pancreas regulated glucose successfully. Now researchers are testing the device’s ability to keep glucose levels stable during exercise, when muscles turn glucose into energy.