Effects of acute hypoglycaemia on auditory information processing in adults with Type I diabetes

Acute hypoglycaemia in humans causes general impairment of cognitive function, but information about its effects on more specific cognitive processes is limited.

Basic aspects of auditory function were studied in 15 adults with uncomplicated Type I (insulin-dependent) diabetes mellitus. Two separate hyperinsulinaemic glucose clamp procedures were done on different study days, in a counterbalanced fashion, either maintaining euglycaemia (blood glucose 5.0 mmol x l(-1)) or inducing hypoglycaemia (blood glucose 2.6 mmol x l(-1)). During each study, the subjects performed a battery of auditory and cognitive function tasks.

Hypoglycaemia caused deterioration in mental efficiency as assessed by Digit Symbol (p<0.001) and Trail Making B (p=0.004) tasks. Acute hypoglycaemia also caused deterioration in one of three measures of simple auditory processing (single-tone loudness, p=0.001) and in auditory temporal processing (p=0.007). The amplitude and latency of auditory N100, P200 and P300 event-related potentials were not affected, but the amplitude of the N240 potential was reduced during acute hypoglycaemia.

Our findings are consistent with other recognised disruptive effects of acute hypoglycaemia on sensory information processing in non-diabetic and diabetic adults, including adverse effects on auditory information processing in non-diabetic subjects. These derangements have implications for the everyday activities of people with Type I diabetes who are frequently exposed to acute hypoglycaemia.