ESTIMATION OF GLUCOSE BY GOD-POD
Glucose is the central molecule in carbohydrate metabolism and all the major pathways of carbohydrate metabolism are connected with it. Glucose is utilized as If a source of energy, it is synthesized from non-carbohydrate precursors and stored as glycogen to release glucose as and when the need arises. An adult human body contains about 18 g free glucose - an amount just sufficient to meet the basal energy requirements of the body for one hour.
1. Sources of blood glucose:
Dietary sources :
The dietary carbohydrates are digested and absorbed as monosaccharides (glucose, fructose etc.). The liver is capable of converting fructose and galactose into glucose, which can readily enter blood.
Gluconeogenesis :
Lactate, glycerol, propionate and some amino acids are good precursors for glucose synthesis (gluconeogenesis) that actively occurs in liver and kidney. Gluconeogenesis continuously adds glucose to the blood. The Cori cycle converts muscle lactate to glucose in liver.
Glycogenolysis :
Degradation of glycogen in liver produces free glucose. Muscle glycogenolysis does not form sufficient glucose due to lack of the enzyme glucose 6-phosphatase. Due to the limited presence of glycogen in liver, the contribution of liver glycogenolysis to blood glucose is limited and can meet only the short intervals of emergency. An adult liver (weighing about 1.5 kg) can provide only 40-50 g of blood glucose from glycogen, to meet the body requirements for a few hours.
Glucose is primarily derived from glycogenolysis (of hepatic glycogen) between the meals. Gluconeogenesis becomes a predominant source of glucose in late night (after depletion of hepatic glycogen).
During day time, gluconeogenesis may be more or less active, depending on the frequency of consumption of snacks, coffee, tea, fruit juices etc.
A healthy individual is capable of maintaining the blood glucose concentration within a narrow range. The fasting blood glucose level in a post-absorptive state is 70-100 mg/dl (plasma glucose 80-120 mg/dL). Following the ingestion of a carbohydrate meal, blood glucose may rise to 120-140 mg/dL.
