The effects of blood sugar level changes on cognitive function, affective state, and somatic symptoms.

In an attempt to find out whether decreased blood sugar level is associated with impaired cognitive function, adverse emotional changes, or somatic symptoms, 35 subjects who suspected that they had hypoglycemia were given 5-hr glucose tolerance tests (GTTs). Nine blood samples were taken during the GTT, and the subject's mood, Serial Sevens Test (SST) performance, and somatic symptom reports were recorded on each occasion of sampling. The subjects reported significantly more negative affect and somatic symptoms after glucose nadir than before nadir. SST performance deteriorated at glucose nadir. These effects were more pronounced for subjects with high hypoglycemic index scores than for subjects with low index scores. The impairment in SST performance was greater for subjects who showed rapid decreases in blood sugar than for subjects who showed slow decreases. Dividing subjects by high and low nadirs did not reveal any differences in symptomatology.