Reaction Time Impairment in Insulin-Dependent Diabetes: Task Complexity, Blood Glucose Levels, and Individual Differences

The effects of hypoglycemia on cognitive processing speed as measured by reaction time (RT) were evaluated in 25 adults (13 women and 12 men) with insulin-dependent diabetes. Simple, choice, and complex RT tasks were administered in a single-blind, repeated measures cross-over design. On the experimental day, participants performed tests at euglycemia (80-120 mg/dl), then at mild (55-70 mg/dl) and moderate (33-50 mg/dl) hypoglycemia, and again at euglycemia. On the control day, participants performed tests 4 times at euglycemia. Three months later, 15 participants repeated the experimental day protocol. Results indicated significant increases in RT at moderate hypoglycemia. Individuals varied greatly in their response to mild and moderate hypoglycemia. Individual differences in hypoglycemia sensitivity were not reliable across time and did not correlate with individual difference variables. Complex and simple RT tasks were equally sensitive to cognitive slowing associated with hypoglycemia.