Thursday, October 26, 2006

Why Low Blood Sugar Affects The Brain?

Hypoglycemia occurs when your blood sugar, called glucose, is abnormally low.

Why Low Blood Sugar Affects The Brain?

Like most animal tissues, brain metabolism depends primarily on glucose for fuel in most circumstances. A limited amount of glucose can be derived from glycogen stored, but it is consumed within minutes. For most practical purposes, the brain is dependent on a continual supply of glucose diffusing from the blood into the interstitial tissue within the central nervous system and into the neurons themselves.

Therefore, if the amount of glucose supplied by the blood falls, the brain is one of the first organs affected. In most people subtle reduction of mental efficiency can be observed when the glucose falls below 65 mg/dl . Impairment of action and judgement usually becomes obvious below 40 mg/dl . Seizures may occur as the glucose falls further. As blood glucose levels fall below 10 mg/dl (0.55 mM), most neurons become electrically silent and nonfunctional, resulting in coma.

Brief or mild hypoglycemia produces no lasting effects on the brain, though it can temporarily alter brain responses to additional hypoglycemia. Prolonged, severe hypoglycemia can produce lasting damage of a wide range. This can include impairment of cognitive function, motor control, or even consciousness. The likelihood of permanent brain damage from any given instance of severe hypoglycemia is difficult to estimate, and depends on a multitude of factors such as age, recent blood and brain glucose experience, concurrent problems such as hypoxia, and availability of alternative fuels. The vast majority of symptomatic hypoglycemic episodes result in no detectable permanent harm.