Cerebral metabolic effects of glycerol infusion in diabetics with stroke

Abstract Measurement of cerebral blood flow and metabolism before and after intravenous infusion of 10% glycerol was investigated in 22 patients with acute cerebral ischemia, 10 of whom had diabetes mellitus and 12 of whom did not. In diabetic patients, resulting increases of hemispheric blood flow and reduction of oxygen consumption and CO 2 production were not significant whereas these changes in the non-diabetic group were significant. In diabetics cerebral glucose consumption and glucose:oxygen utilization ratio increased significantly but remained unchanged in non-diabetics. Following glycerol infusion, release of free fatty acids and inorganic phosphate from the infarcted hemisphere was diminished or reversed in both groups. It is postulated that the differences in cerebral metabolic responses to glycerol among an acute stroke population with diabetes compared to a similar group with acute stroke but without diabetes may be accounted for by the depressed cerebral glucose consumption in diabetics resulting from elevated blood levels of β-hydroxybutyrate, which tends to be reversed by the antiketogenic effect of glycerol and/or by the greater rise in blood glucose in diabetics following glycerol administration. Hence glycerol would not reduce cerebral oxygen consumption and CO 2 production in the diabetics as much as in the non-diabetics although the release of cerebral free fatty acids and inorganic phosphate from the infarcted brain would be reduced or reversed in both groups. It is concluded that intravenous glycerol infusion may improve uncoupled cerebral oxidative phosphorylation or provide the brain with an additional source of high energy phosphate bonds (ATP production) such as glycerol phosphate.