EEG TOPOGRAPHY DURING INSULIN-INDUCED HYPOGLYCEMIA IN PATIENTS WITH INSULIN-DEPENDENT DIABETES-MELLITUS

A group of young patients with insulin-dependent diabetes mellitus (n = 14; 8 men, 6 women; 33.1 +/- 8.9 years) were examined by topographic EEG mapping under normoglycemic and hypoglycemic conditions (glucose levels after intravenous insulin injection down to 32.6 +/- 7.6 mg/dl) . From the clinical aspect, 7 of them had a good and 7 had a poor awar eness of hypoglycemia. During hypoglycemia, a decrease in alpha activi ty (p < 0.05), an increase in delta (p < 0.05), and especially in thet a activity (p < 0.05) were found. The most sensitive parameter was the alpha/theta ratio. In the range of slight hypoglycemia (50-60 mg/dl) the increase in delta and theta activity showed a topographic maximum in lateral frontal regions. During deep hypoglycemia there was a topog raphic maximum of slow frequencies in posterior parts of the brain (ce ntrotemporal to parieto-occipital regions). The differences between th e group with good and with poor awareness of hypoglycemia were most pr onounced during slight hypoglycemia in C3, C4, and Pt (p < 0.05). At l ower glucose levels group distinction was no longer possible. These EE G changes correspond to a temporary organic brain syndrome.