1. A polypeptide hormone secreted by the islets of Langerhans and functioning in the regulation of the metabolism
of carbohydrates and fats, especially the conversion of glucose to glycogen, which lowers the blood glucose level.
Any of various pharmaceutical preparations containing this hormone that are derived from the pancreas of certain animals or
produced through genetic engineering and are used in the medical treatment and management of diabetes mellitus (type I).
Generic Name: insulin
Brand Name: various
Drug Class And Mechanism:
Insulin is a naturally-occurring hormone secreted by the pancreas. Insulin
is required by the cells of the body in order for them to remove and use glucose from the blood. From glucose the cells produce
the energy that they need to carry out their functions. Researchers first gave an active extract of the pancreas containing
insulin to a young diabetic patient in 1922, and the FDA first approved insulin in 1939. Currently, insulin used for treatment
is derived from beef and pork pancreas as well as recombinant (human) technology. The first recombinant human insulin was
approved by the FDA in 1982.
Patients with diabeter mellitus
have an inability to take up and use glucose from the blood, and, as a
result, the glucose level in the blood rises. In type 1 diabetes, the pancreas cannot produce enough insulin. Therefore, insulin
therapy is needed. In type 2 diabetes, patients produce insulin, but cells throughout the body do not respond normally to
the insulin. Nevertheless, insulin also may be used in type 2 diabetes to overcome the resistance of the cells to insulin.
By increasing the uptake of glucose by cells and reducing the concentration of glucose in the blood, insulin prevents or reduces
the long-term complications of diabetes, including damage to the blood vessels, eyes, kidneys, and nerves. Insulin is administered
by injection under the skin . The subcutaneous tissue of the abdomen is preferred because absorption of the insulin is more
consistent from this location than subcutaneous tissues in other locations.
Regular (rapid onset of action, short duration of action) and NPH (slower onset of action, longer duration of action)
human insulin are the most commonly-used preparations. Regular insulin has an onset of action (begins to reduce blood sugar)
within 30 minutes of injection, reaches a peak effect at 1-3 hours, and has effects that last 6-8 hours.
NPH insulin is an insulin with an intermediate duration of action. It has an onset of action starting
about 2 hours following injection. It has a peak effect 4-12 hours after injection, and a duration of action of 18-26 hours.
Lente insulin also is an insulin with an intermediate duration of action. It has an onset of action
2-4 hours after injection, a peak activity 6-12 hours after injection, and a duration of action of 18 to 26 hours. Ultralente
insulin is a long-acting insulin with an onset of action 4-8 hours after injection, a peak effect 10-30 hours after injection,
and a duration of action of more than 36 hours.
An ultra rapid-acting insulin, insulin lispro is a chemically-modified, natural insulin. It was approved
by the FDA in June, 1996. As compared to regular insulin, insulin lispro has a more rapid onset of action, an earlier peak
effect, and a shorter duration of action. It reaches peak activity 0.5-2.5 hours after injection. Therefore, insulin lispro
should be injected 15 minutes before a meal as compared to regular insulin which is injected 30-60 minutes before a meal.
Insulin aspart and insulin glargine are both human insulin that have had their chemical composition slightly altered.
The chemical changes provide insulin aspart with a faster onset of action (20 minutes) and a shorter duration of action (3-5
hours) than regular human insulin. It reaches peak activity 1-3 hours after injection. Insulin glargine has a slower onset
of action (70 minutes) and a longer duration of action (24 hours) than regular human insulin. Its activity does not peak.
A hormone secreted by the pancreas that regulates the levels of sugar in the blood.
Persons suffering from diabetes mellitus
may receive periodic or daily injections of insulin as a treatment
for the disease.
A natural hormone made by the pancreas that controls the level of the sugar glucose in the blood. Insulin permits
cells to use glucose for energy. Cells cannot utilize glucose without insulin.
Diabetes: The failure to make insulin or to respond to it constitutes diabetes mellitus. Insulin is made specifically
by the beta cells in the islets of Langerhans in the pancreas. If the beta cells degenerate so the body cannot make enough
insulin on its own, type I diabetes results. A person with this type of diabetes must inject exogenous insulin (insulin from
sources outside the body).
In type II diabetes, the beta cells produce insulin, but cells throughout the body do not respond normally to it.
Nevertheless, insulin also may be used in type II diabetes to help overcome the resistance of cells to insulin.
By reducing the concentration of glucose in the blood, insulin is thought to prevent or reduce the long-term complications
of diabetes, including damage to the blood vessels, eyes, kidneys, and nerves.
Learn more about diaetes mellitus.
Types of Insulin: Currently, insulin is available from bovine (beef), porcine (pork), and recombinant (human) sources.
Regular (rapid onset, short-acting) and NPH (slower onset, longer duration) human insulin are the most commonly-used preparations.
An ultrarapid-acting insulin analog, insulin lispro injection (Humalog(r)) is a chemically-modified, natural insulin. It was
approved by the FDA in June, 1996.
Insulin is administered by injection via the subcutaneous (under the skin) route. Regular insulin acts within 30
minutes, and its effects last 6 to 8 hours. The maximal effect occurs 1 to 3 hours following the injection.