Mathematics of Glucohomeostasis

During normal conditions the basal glucose requirement amounts to 2 mg/kg/min. This results in 10 gramms per hour for a normal weight adult of 75 kg. The brain requires around 5-6 g/h, day or night, during rest or "work". About 4 g/h are used by the muscles, fat tissue, the organs (liver, heart) and the red blood cells, mostly requiring insulin for glucose uptake. The liver thus has to produce 10 g/h, mostly achieved by glucagon.

This simple calculation demonstrates the essential and critical requirement of a minimal arterial blood glucose concentration of 50 mg/dl in order to guarantee the demands of the brain for proper functionality. These are not met at 40 mg/dl and thus would cause neurological symptoms. Normal brain blood flow and cardiac output are essential. Attenuation of cardiac function (insufficiency, cardiomyopathy) and attenuation of cerebral blood flow (stroke, sclerosis) demonstrate the fragile equilibrium in case of prevailing hypoglycemia.

"Stress-Hyperglycemia" during the postaggressive metabolic state essentially means the physiological adaptation to jeopardized cerebral blood flow in order to meet the fuel needs by the brain. This is achieved by a biochemical centralisation of the glucose metabolism analogous to the hemodynamic centralisation of the circulation during shock (cardiogenous, hemorrhagic, hypovolemic). Metabolic centralisation physiologically resembles a glucagon-mediated "endogenous infusion of glucose".

Literature Glucohomeostasis