ABSTRACT
Glucose is the single common substrate that can be used by all tissues as an energy source. Although most tissues can also use fatty acids for energy, nervous tissue, red cells (erythrocytes), kidney, and, in normal circumstances, brain have an obligatory requirement for glucose (Table 2.1). It is for this reason that the maintenance of plasma glucose within a narrow concentration range (Table 2.2) is fundamental to health. The normal distribution range of blood glucose in the UK population is 4.1-5.9 mmol/L (74-106 mg/dL) with a slightly higher range for adults of 60 years and above of 4.4-6.4 mmol/L (80-115 mg/dL). Pathological consequences ensue when the glucose concentration lies
Tissue Immediately postprandial 2-5 hours postprandial
Brain Glucose Glucose
Red blood cells Glucose Glucose
Nervous tissue Glucose Glucose
Kidney Glucose Glucose (fatty acids)
Skeletal muscle Glucose Fatty acids (glucose)
Liver Glucose Fatty acids (glucose)
Heart Glucose Fatty acids (glucose)
Lung Glucose Fatty acids (glucose)
Gastrointestinal tract Glucose Fatty acids, glucose
Adipose Glucose Fatty acids (glucose)
outside of this range for prolonged periods; hypoglycemia is characterized by impaired mental function and severe hypoglycemia by coma, while hyperglycemia, particularly chronic hyperglycemia, promotes the insidious pathology of diabetes mellitus.
