Glucose is a major source of energy in our body mainly formed by carbohydrates and from fats and proteins with a chemical formula C6H12O6 and is a simple sugar belonging to the group of carbohydrates called mono-saccharides.Simple sugar means it cann’t be broken down into other sugars.Other names are dextrose,grape sugar and blood sugar.
When glucose is not immediately required for energy the extra glucose is either converted by the liver and muscle cells into glycogen, or converted into body fat ,when needed is converted back and is metabolized in tissues to generate the adenosine triphoshate (ATP) which provides energy.Glucose is stored as glycogen until the cells have stored as much glycogen as they can.When the glycogen storing cells(primarily liver & muscle cells) are saturated with glycogen,the additional glucose is converted into fat in liver and fat cell-sand stored as fat.
Glucose enters the bloodstream by absorption from the small intestine.Our brain is very sensitive to glucose shortages so the blood glucose level commonly referred to as blood sugar level is kept constant by converting excess glucose into glycogen,into body fat or metabolized to release heat.
Glucose Sources:We get most of our glucose from digesting the sugar and starch in carbohydrates and all major dietary carbohydrates contain glucose. Complex carbohydrates, such as starches, are the best source of glucose in the diet.Breakdown of carbohydrates e.g. starch yields mono- and disaccharides, most of which is glucose,its eventualy oxidized to form carbon-dioxide and water yielding energy mostly in the form of ATP as mentioned above.Foods like rice,breads,cereals, pasta, grain, potatoes, fruits,honey, a few vegetables, and sugary sweets are good sources of carbohydrates & ultimately a source of glucose.
Sources Of Carbohydrates:Only three major sources of carbohydrates exist in the normal human diet.They are sucrose which is the disaccharide commonly known as cane sugar.Lactose which is a disaccharide in milk; and starches which are large polysaccharides present in all nonanimal foods particularly in grains.
Normal blood glucose level in mg/dL
- On waking up(before breakfast) →80 to 120
- Before meals→ 80 to 120
- 2hrs After meals →160 or less
- At bedtime →100 to 140
The ideal values in mmol/L are:
- Before meals 4to7mmol/L
- 90min after a meal <10mmol/L
- At bedtime around 8mmol/L
Blood glucose level
Normal blood glucose level:The blood sugar level is the amount of glucose (sugar) in the blood. It is also known as serum glucose level.It is expressed as millimoles per litre (mmol/l).
Normally, blood glucose levels stay within narrow limits throughout the day: 4 to 8mmol/l. But they are higher after meals and usually lowest in the morning.
Diabetic patients show blood sugar level outside these limits until treated.Blood glucose level can exceed sometimes this normal range in such people even having diabetes under control.
Regulation of blood glucose
After a meal the amount of glucose in the bloodstream rises.The regulation of blood glucose level is intimately related to two hormones;insulin and glucagon secreted by abdominal gland called pancreas.
INSULIN:It regulates glucose level in the blood by promoting glucose absorption into liver and fat cells.Its normally produced in response to raised glucose level followed a meal.Failure of insulin production results in diabetes mellitus.In this case insulin is replaced by injection or infusion pump for the treatment of diabetes mellitus.Insulin can’t be taken orally becaused its destroyed by stomach acid.Conversely,excessive production of insulin causes hyperglycemia,also if too high dose of insulin is taken it results in hyperglycemia.
GLUCAGON:Glucagon hormone stimulates the breakdown of stored glycogen into glucose when the blood level of glucose is low.An injection of glucose or glucagon is given as an emergency treatment in severe hypoglycaemia which opposes the effect of insulin.
It represents insulin is helpful in Glycogenesis which is the process of glcogen formation for storage from excessive glucose in blood and glucagon is helpful in Glycogenolysis(removal of stored glycogen) which means the breakdown of cell’s stored glycogen into glucose again when needed.