Normal blood glucose is ranging from 60-110 mg/dl (3.5-6.8 mmol/L).This normal range is kept through the effect of pancreatic hormone insulin and it’s antagonists.
Insulin: It is a peptide hormone produced by the beta cells of islets of langerhans of the pancreas. This hormone is released after food ingestion and glucose absorption. It tends to decrease blood glucose level through increasing entry of glucose into the tissues, such as muscles and adipose tissue.
Insulin antagonists includePancreatic hormone Glucagone, produced by the alpha cells of islets of langerhans.It’s release is stimulated by hypoglycemia. It acts through stimulation of phosphorylase enzyme ( a key enzyme in glycogen breakdown or glycogenolysis, and it stimulate gluconeogenesis).
Anterior pituitary gland hormones Growth hormone which increases the blood glucose through decreasing uptake of glucose into muscles and stimulation of glyconenolysis. Glucosteroids: ACTH secreted by anterior pituitary increases gluconeogenesis.
Thyroid gland: thyroxine which has controlling effect. Hypothyroidism is associated with hyperglycemia (due to decrease utilization of glucose). Hyperthyroidism is associated with a tendency to decrease blood glucose.
Diabetes Mellitus (DM) It is a clinical condition associated with increasing blood glucose level, usually above 120 mg/dl. It could be due to deficient insulin production, and is called Type I DM (Juvenile DM). It could be due to chronic pancreatitis, and is called Type II DM (secondary DM).
Diabetes mellitus is associated with: 1- hyperglycemia (increased blood glucose). 2- Glycosuria (appearance of glucose in urine). 3- polyuria, thirst.
Cushing’s Syndrome:Due to increased production of ACTH (anterior pituitary tumor).
Acromegaly: This is due to a tumor of the anterior pituitary, producing excessive growth hormone