Hypoglycemic thresholds for cognitive dysfunction in humans

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From: Diabetes(Vol. 39, Issue 7)
Publisher: American Diabetes Association
Document Type: Article
Length: 5,048 words

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Abstract :

The effect of hypoglycemia, abnormally low blood glucose levels, on cognitive function was assessed. Hypoglycemia was induced by the administration of insulin in 19 healthy adult volunteers. The cognitive decision-making process in response to auditory (sound) and visual stimuli can be measured by changes in brain electrical activity, specifically, the P300 cerebral event-related potential. P300 and the reaction time were assessed in response to a visual stimulus in 10 patients with blood glucose at normal levels, and with blood glucose reduced to 3.3 and 2.6 millimolar (mM) during administration of insulin. Reduction of blood glucose levels to 3.3 mM did not alter P300 or the reaction time. However, reduction of blood glucose to 2.6 mM increased the latency of P300, the period of time before the onset of decision-making processes, and prolonged the reaction time. Similar results were obtained in nine additional patients who were presented with both auditory and visual stimuli. The prolongation of P300 was not immediately corrected by rapidly raising blood glucose levels to normal, but recovered to normal 45 to 75 minutes after the ingestion of a carbohydrate-containing meal. Another form of brain electrical activity P140, which reflects sensory processes, was not altered during hypoglycemia. Changes in reaction time were related to changes in p300 latency, suggesting that hypoglycemia affects only decision-making and not motor processes. Thus, hypoglycemia induced by insulin impairs cognitive function when blood glucose levels are decreased between 3.3 and 2.6 mM. Specifically, decision-making processes and not sensory or motor processes are affected by hypoglycemia. Both auditory and visual P300 and reaction times are altered, and brain function recovers 45 to 75 minutes after blood glucose levels return to normal. Individuals may differ in their sensitivity to adverse effects of hypoglycemia on cognitive function. (Consumer Summary produced by Reliance Medical Information, Inc.)

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Gale Document Number: GALE|A9329017