Progressive hypoglycemia's impact on driving simulation performance - Occurrence, awareness, and correction

OBJECTIVE - Progressive hypoglycemia leads to cognitive-motor and driving i mpairments. This study evaluated the blood glucose (BG) levels at which dri ving was impaired, impairment was detected, and corrective action was taken by subjects, along with the mechanisms underlying these three issues. RESEARCH DESIGN AND METHODS - There were 37 adults with type 1 diabetes who drove a simulator during continuous euglycemia and progressive hypoglycemi a. During testing,driving performance, EEG, and corrective behaviors (drink ing a soda or discontinuing driving) mere continually monitored, and BG, sy mptom perception, and judgement concerning impairment were assessed every 5 min. Mean +/- SD euglycemia performance was used to quantity z scores for performance in three hypoglycemic ranges (4.0-3.4, 3.3-2.8, and <2.8 mmol/l ). RESULTS - During all three hypoglycemic BG ranges, driving was significantl y impaired, and subjects were aware of their impaired driving. However, cor rective actions did not occur until BG was <2.8 mmol/l. Driving impairment was related to increased neurogenic Symptoms and increased theta-wale activ ity Awareness of impaired driving was associated fifth neuroglycopenic symp toms, increased beta-wave activity and awareness of hypoglycemia. High beta and low theta activity and awareness of both hypoglycemia and the need to treat low BG influenced corrective behavior. CONCLUSIONS - Driving performance is significantly disrupted at relatively mild hypoglycemia, yet subjects demonstrated a hesitation to take correctiv e action. The longer treatment is delayed, the greater the neuroglycopenia (increased theta), which precludes corrective behaviors. Patients should tr eat themselves while driving as soon as low BG and/or impaired,driving is s uspected and should not begin driving when their BG is in the 5.0-4.0 mmol/ l range without prophylactic treatment.