Insulin is secreted by the Beta cells of the Islets of Langerhans, which are highly vascularised cells scattered throughout the pancreas.
Diabetes mellitus (DM) is a chronic metabolic disorder, resulting from insulin deficiency characterised by hyperglycaemia, and altered metabolism of carbohydrates, protein and lipids. The incidence of DM in India is fairly high, and it was labelled as the Diabetes capital of the World. Predisposition to DM is inherited, and the genetic factors are complex. There are two recognised types of DM:
(i) Type I Insulin-dependent type or (IDDM), juvenile onset type.
(II) Type II or maturity-onset diabetes (NIDDM) , maturity onset type.
Type I usually occurs in non-obese persons, before the age of 30 years and circulating insulin is usually absent. The Type II usually occurs after the age of 40 years, and obesity is a major risk factor. Further, Gestational diabetes refers to the onset of diabetes in women during pregnancy.
Insulin was first isolated by Banting and Best in 1921, and used in the treatment of DM in 1922, later it was completely synthesized in 1966.
Mode of action of Insulin
The major effects of insulin are initiated by the attachment of the insulin molecule to the insulin receptor on the cell surface. This hormone-receptor interaction is reversible. Various fast-acting, intermediate-acting, and long-acting preparations of insulin are available. Today newer insulins and human insulins are also available.
Their detailed consideration is beyond the scope of this text. as It is a highly specialised process.
Adverse reactions include hypoglycemia, insulin allergy, neuropathy, insulin presbiopia, insulin resistance, and obesity.
Therapeutic uses include Diabetes mellitus, Schizophrenia. anorexia nervosa.
Oral hypoglycaemic agents (The older and newer agents) are mainly employed in the management of Type II or maturity onset diabetes mellitus. In addition, the management of DM includes physical exercise, regulation of diet, and management of complications involving the heart, brain and the eyes.