INSULIN
Insulin is a hormone produced by the beta-cells of the pancreas.
It is a protein with a molecular weight of approximately 5700
kDa. It is formed from proinsulin after cleavage into insulin
and C-peptide (Fig 1).
The normal insulin secretion is 0.5-0.7 units/kg per day.
Fig 1: Insulin has two chains A and B and during its production.
A third chain of peptides called C Peptide links these. C peptide
is removed before Insulin is secreted into the blood.
Physiological
Functions of Insulin
-
Stimulates entry of glucose into cells for utilization as energy
source.
-
Stimulates entry of amino acids into cells, enhancing protein
synthesis
-
Enhances fat storage and prevents mobilization of fat for energy
(lipolysis)
-
Promotes storage of glucose as glycogen in muscle and liver
cells (glycogenesis)
-
Inhibits formation of glucose from non carbohydrates (gluconeogenesis)
Indications
for Insulin Therapy
Absolute
-
All individuals with Type 1 diabetes
-
Type 2 diabetes not adequately controlled by other forms of
therapy (drugs, diet and exercise)
-
Malnutrition related diabetes mellitus
Intermittent
-
Gestational diabetes
-
Individuals with Type 2 diabetes during periods of physiological
stress (major surgery, infection)
-
Diabetic ketoacidosis (DKA)
-
Hyperosmolar hyperglycemic nonketotic syndrome (HHNS)
-
Diabetics with tuberculosis often do better with insulin.
-
Secondary diabetes (pancreatitis, corticosteroids)
Last
updated on 13-12-2002
