Recovery of cognitive function and mood after severe hypoglycemia in adults with insulin-treated diabetes

OBJECTIVE - Acute hypoglycemia in humans impairs cognitive functions and al ters mood states. The time required for cognitive functions and moods to re turn to normal after an acute episode of severe hypoglycemia is unknown. RESEARCH DESIGN AND METHODS - Cognitive functions and moods were studied pr ospectively in 20 subjects with insulin-treated diabetes who had recently e xperienced a spontaneous episode of severe hypoglycemia ("hypo" subjects) a nd 20 matched control subjects with insulin-treated diabetes who had not ex perienced severe hypoglycemia during the preceding year. The hypo subjects had a history of a greater number of episodes of severe hypoglycemia (P = 0 .000). Cognitive function tests and mood scales were administered at 1.5, 9 , and 30 days after the severe hypoglycemia and at similar intervals for th e control subjects. RESULTS - For most of the cognitive tests, no evidence of a "hangover" effe ct of the acute hypoglycemia on cognitive function was observed (P > 0.05). A trend was noted for levels of hedonic tone (P = 0.082) and energetic aro usal (P = 0.053) to improve with time in the hypo subjects but not in the c ontrol subjects. However, the hypo subjects had chronically elevated levels of depression (P = 0.011) and anxiety (P = 0.049) and persistently perform ed more poorly in several cognitive tests, such as the Digit Symbol Test (P = 0.009) and the Stroop Task (P = 0.007). CONCLUSIONS - These results suggest that, in general, recovery from any acu te cognitive decrement after severe hypoglycemia was complete by 1.5 days. The cognitive decrements and altered mood states noted in the hypo subjects may be persistent and may be a consequence of previous exposure to recurre nt episodes of severe hypoglycemia.