DISRUPTIVE EFFECTS OF ACUTE HYPOGLYCEMIA ON SPEED OF COGNITIVE AND MOTOR-PERFORMANCE

OBJECTIVE - To directly examine whether hypoglycemia differentially sl ows cognitive versus motor function, to evaluate the reliability of hy poglycemic-related slowing, and to examine factors contributing to ind ividual differences. RESEARCH DESIGN AND METHODS- IDDM subjects (n = 1 0) were administered a pure cognitive and a pure motor neuropsychologi cal test at euglycemia (5.4 mmol), blood glucose nadir (2.6 mmol), pos tnadir (3.6 mmol), and again at euglycemia (6.7 mmol). To assess the p ractice effect, matched control subjects were tested at similar time i ntervals. RESULTS- Concurrent and test-retest reliability for all test s was robust (r = 0.68-0.94). Only cognitive tasks demonstrated impair ment at nadir (P < 0.04). Individual differences, in terms of cognitiv e impairment, were significantly correlated with levels of blood gluco se at nadir and baseline performance. CONCLUSIONS - Cognitive tasks ap pear to be more sensitive to neuroglycopenia than motor tasks. Cogniti ve impairment caused by hypoglycemia is reliable and differs across su bjects. Individuals who show reliable sensitivity to cognitive impairm ents of hypoglycemia should avoid moderately low blood glucose levels.