Psychomotor performance during insulin-induced hypoglycemia.

Subjects were given intravenous injections of insulin and/or saline on separate occasions and then tested on a pursuit-tracking task. Seven subjects showed clear clinical signs of hypoglycemia which were accompanied by a plasma glucose concentration of 32 mg/dl or less and by impaired tracking performance. Seven subjects showing no hypoglycemic signs despite insulin, and seven subjects receiving saline injections, showed no impairment in tracking. Impairment lasted from about the 15th to the 60th minute following injection, and was more readily apparent in response execution than response selection. There were no changes in accuracy of performance. Possible explanatory mechanisms, including neuroglycopenia, are discussed, and some implications for driving performance are noted.