A system is disclosed for optimizing exercise training of a diabetic exerciser. Computer software accepts physical status data and, in preferred embodiments, information regarding available exercise equipment, and formulates therefrom an optimized diet and exercise program, which is downloaded to an MP3 player or similar portable electronic device. The portable device directs the exerciser during workouts, while communicating with a blood glucose monitor and preferably with a heart rate monitor so as to monitor the exerciser's blood glucose level and heart rate during exercise, and warn the exerciser if the blood glucose level exceeds specified bounds. The portable device records a log of physiological data, exercise performed, and food consumed, for later upload to the computer and possible transmission to a healthcare provider. Preferred embodiments include only software. Other embodiments include a portable device, blood glucose monitor, heart rate monitor, or communications enabler.