THE INFLUENCE OF HYPOGLYCEMIA ON REGIONAL CEREBRAL BLOOD-FLOW AND CEREBRAL VOLUME IN TYPE-1 (INSULIN-DEPENDENT) DIABETES-MELLITUS

The effect of moderate hypoglycaemia (venous blood glucose 2.0 +/- 0.2 mmol/l; mean +/- SD) on regional cerebral blood flow and cerebral vol ume was studied in a group of ten right-handed patients with Type 1 (i nsulin-dependent) diabetes mellitus (age 26.0 +/- 2.4 years, duration 18.4 +/- 3.8 years) using an intravenous Xenon 133 single photon emiss ion computed tomography technique. After 10 min of hypoglycaemia, glob al cerebral blood flow had increased to 55.8 +/- 4.5 ml . 100 g-1 . mi n-1 compared to the initial normoglycaemic flow of 49.5 +/- 3.7 ml . 1 00 g-1 . min-1 (p < 0.01). A further increase in global cerebral blood flow to 59.5 +/- 4.5 ml . 100 g-1 . min-1 (p < 0.05) occurred 15 min after normalization of the blood glucose level. The global cerebral bl ood flow change from before hypoglycaemia to after recovery was invers ely related to the initial glucose level. No change in the relative di stribution of the regional cerebral blood flow was found between the m easurements. The cerebral blood flow was significantly higher in the r ight hemisphere compared with the left hemisphere (2.3, 1.6 and 2.2 %, respectively; p < 0.05) in all measurements. Deeper hypoglycaemia was associated with a more pronounced decrease in brain volume, while the length of the restitution time after hypoglycaemia correlated with a volume increase. Due to influences with opposite effects there was no mean change in the brain volume.