OBJECTIVE - Experimentally induced hypoglycemia in humans causes progressiv
e but reversible cognitive dysfunction, but it is not known to what extent
neuropsychological tests index abilities of cognitive functioning that are
important in everyday life. This study examines the effects of acute insuli
n-induced hypoglycemia on attention and intelligence in nondiabetic humans.
RESEARCH DESIGN AND METHODS - A hyperinsulinemic glucose clamp was used to
achieve controlled euglycemia (4.50 [0.22] mmol/l) and hypoglycemia (blood
glucose 2.59 [0.19] mmol/1) in 20 healthy volunteers. Subjects were Studied
on two occasions in a counterbalanced order. During each study condition,
subjects completed parallel tests of cognitive function. Cognitive function
was assessed by the Test of Everyday Attention and Raven's Progressive Mat
RESULTS - Hypoglycemia induced a significant deterioration in tests Sensiti
ve to both visual and auditory selective attention. During hypoglycemia, at
tentional. flexibility deteriorated and speed of information processing was
delayed. Sustained attention was preserved and intelligence scores did not
deteriorate during hypoglycemia.
CONCLUSIONS - During hypoglycemia, a significant deterioration occurs in at
tentional abilities, whereas fluid intelligence is preserved. On the basis
of these results, it can be surmised that many complex attention tasks rele
vant to everyday life are impaired during moderate hypoglycemia.