Twenty-four insulin-dependent diabetic pediatric subjects were studied for 1444 nights for detection of nocturnal hypoglycemia with the Teledyne Sleep Sentry (Teledyne Avionics, Charlottesville, Virginia): a wristwatch-like unit that measures absolute changes in skin temperature and decreases in galvanic skin resistance, indicators of hypoglycemia. The device detected 42 of 46 recognized hypoglycemic episodes. One hundred fifty alarms were sounded without evidence of hypoglycemia, probably due to night sweating. Twenty-five percent of the subjects experienced unacceptable cutaneous reactions, presumably due to metallic iontophoresis.