ADA CONFERENCE: Mild hypoglycemia [insulin reaction/insulin shock- ed] [under 80 mg/dl or under 4.4 mmol/L] Impairs Driving In Type I Diabetics

CHICAGO, IL -- June 16, 1998 -- For people with Type I diabetes, episodes of even mild hypoglycemia [insulin reaction/insulin shock- ed] can make driving dangerous, according to researchers at the University of Virginia Health Sciences Center.

The finding was reported today at the annual meeting of the American Diabetes Association in Chicago.

"Based on the results of this study, we are recommending that people with diabetes should never get behind the wheel of a car if their blood glucose level is 80 mg/dl or less," said Daniel Cox, professor of psychiatric medicine at U.Va. and the study's lead investigator. "If they are driving and suspect that their blood glucose is getting low, they should pull over and treat it immediately."

Prior to the U.Va. study, doctors thought that a blood glucose level of less than 60mg/dl could result in impaired driving capability. hypoglycemia [insulin reaction/insulin shock- ed] starves the brain of glucose energy, which is essential for proper brain function. Lack of glucose energy to the brain can cause symptoms ranging from headache, mild confusion and abnormal behaviour to loss of consciousness, seizure and coma.

In the U.Va. study, 37 adults with Type I diabetes and a history of severe hypoglycemia [insulin reaction/insulin shock- ed] were tested using a sophisticated driving simulator and a gradual induction of hypoglycemia [insulin reaction/insulin shock- ed]. During the two, 30-minute testing sessions, the subjects' driving performance, electroencephalogram (EEG) and self-treatment of low blood glucose (BG) were continually monitored. At the same time, BG level, symptom perception and judgement concerning driving impairment and the need to self treat were assessed every five minutes.

To objectively assess driving in a controlled environment, the Atari Research Driving Simulator was utilised. The simulator has three, 25-inch computer screens that wrap around the driver, providing a 160- degree visual field, along with a programmed rear view mirror depicting rear traffic. The driving environment was realistic, incorporating a typical-sized steering wheel, gas and brake pedals, seat and seat belt, Cox said.

Driving performance feedback was provided to the subject visually through the three screens that updated at a rate of 60 times per second; aurally through quadraphonic speakers delivering engine, tire and road noises; and kinesthetically through the steering wheel and pedal pressure. Patients were kept blind to the BG manipulations and actual BG levels.

Results of the study show that driving was significantly impaired during all three hypoglycemic BG ranges tested -- 72 to 61, 60 to 50 and less than 50 mg/dl. In addition, subjects were aware of both the need to treat their low BG and their impaired driving. However, actual treatment of low BG did not occur until BG was less than 50 mg/dl.

"Although other studies show that individuals with diabetes have no more driving accidents than the general population, when they do, it is often due to hypoglycemia [insulin reaction/insulin shock- ed]," Cox said. "Prevention of hypoglycemia [insulin reaction/insulin shock- ed]-related accidents relies on both a driver's ability to recognise that BG is low and then to take corrective actions of consuming carbohydrates and/or pulling off the road.

“Our study showed that even when the subjects suspected that their blood glucose was low, they waited too long to treat it, with potentially dangerous consequences."