CARBOHYDRATES AS A CEREBRAL METABOLIC FUEL

The human brain is an extremely active metabolic organ with little end ogenous stores of energy, It is thus dependent on circulating glucose to fuel metabolism and support cognitive functioning, However there is growing evidence that the human brain is able to utilise other non-gl ucose fuels during times of glucose lack, We review the evidence for t he potential of the human brain to use the alternate fuels lactate and beta-hydroxybutyrate, and some recent studies examining the ability o f regions of brain to use non-glucose lipid fuels, The human brain doe s not seem to have the ability to use the gluconeogenic precursor alan ine to any significant degree, Regionality within the brain cam be exa mined in vivo by the use of positron emission tomography, which offers the exciting prospect of studying human brain metabolism in vivo usin g a simple and non-interventional technique, Increased understanding o f the brain's metabolism, the way in which hypoglycaemia is recognised and the manner in which this can be altered in the syndrome of hypogl ycaemia unawareness and deficient counterregulation will help develop further strategies to prevent the clinical problems associated with hy poglycaemia in insulin-dependent diabetic adults and children.