Regulation of blood glucose concentration
Regulation of blood glucose concentration is placed by Liver hormones and intake of Carbohydrate. (hormones like glucagon, growth hormone, cortisol and epinephrine have hyperglycemic effect).
There are two major sources of blood glucose-
- Dietary carbohydrates – absorbed from intestine
- Synthesis of glucose in liver – from glucogenic substances – glycogen, glucogenic amino-acids, glycerol and propionate in ruminants,
Role of Liver in regulation of blood glucose concentration
Liver is the major organ involved in regulating blood glucose. After a carbohydrate meal, the increase in blood glucose is prevented by liver by converting glucose to glycogen and fatty acids. Liver can store glycogen up to 10 to 15% of its weight. During decrease in blood glucose level, liver glycogen is broken down to glucose and released into circulation.
Role of Hormones in regulation of blood glucose concentration
The only hormone that produces high level hypoglycemia is insulin. All other hormones like glucagon, growth hormone, cortisol and epinephrine have hyperglycemic effect.
When insulin effect is removed by pancreatectomy, IGF-I sustains weak insulin activity (but not sufficient to maintain life).
Glucagon and epinephrine promotes glycogenolysis while insulin has antagonistic effect of glycogenesis. Molar ratio of insulin: glucagon rather than the absolute concentration is the determining factor of glycogen breakdown or synthesis. Glucagon stimulates gluconeogenesis from amino acids.
Glucose tolerance test
The capacity of the body’s control mechanisms to regulate blood glucose level can be evaluated by oral glucose tolerance test.
About 1 to 2 g of glucose / kg weight is given orally and blood samples are collected 30 min intervals for 120 or 240 min.
In normal dogs, blood glucose level should reach close to 160 mg/dl in 30 to 60min and the level should reach the baseline normal values by 120 to 180 min.
In horses, by 120 min, the glucose level should reach 175 mg/dl which should return to normal by 360 min.