Insulin is a protein consisting of two amino acid chains joined by two disulfide cross-linkages. It is secreted by the beta cells of the Islets of Langerhans in the pancreas .

Effects of insulin:

In short, insulin brings down the blood glucose level.

A lack of endogenous insulin causes Insulin-Dependent Diabetes Mellitus (IDDM) whereas insulin resistance causes Non Insulin-Dependent Diabetes Mellitus (NIDDM)

Human Insulin

So what’s the deal with insulin?

If you don't know much about insulin you should make a point to rid yourself of that ignorance as Diabetes affects some 15 million North Americans. The use of insulin is not limited to people with Type 1 Diabetes because in some situations people who are able to synthesize their own insulin will require either oral hypoglycemic agents or a subcutaneous injected insulin.

In normal circumstances insulin is secreted by the beta cells in the pancreas and is responsible for moving glucose out of the vascular space and into the cells for use.

There are approximately 5-6 or so different classifications of insulin that are used to treat Diabetes. Humulin L and Humulin N are classified differently depending on what reference text you use.

Rapid-acting Insulin
Common trade names: Humalog
This is a very short acting insulin and should be administered 15 minutes prior to eating as the onset is almost immediate. Humalog peaks in 30-90 minutes and lasts 6 hours. This insulin is very effective and blood glucose levels have to be monitored frequently. The risk of hypoglycemia is high if the recipient fails to eat within 15 minutes of receiving Humalog.

Short-acting Insulin
Common trade names: Humulin R, Novolin R, Novolin R PenFill
In most situations and certainly for at home use Regular insulin is given subcutaneously (into the abdomen usually) and the onset is 30-60 minutes. Regular insulin (SC) peaks at 2-4 hours and lasts 5-7 hours. It is important to eat 15 to 30 minutes after receiving short-acting insulin to avoid hypoglycemic complications.

Intermediate-acting Insulin
Common trade names: Humulin L, Humulin N, NPH insulin, Novolin L, Novolin N
This insulin is normally given in combination with an immediate or short acting insulin as the onset is 1-3 hours and intermediate insulin’s peak at 4-15 hours so on its own producing normal blood glucose levels can be difficult. Eat within 30 minutes of taking intermediate-acting NPH insulin’s.

Long-acting Insulin
Common trade names: Humulin-U Novolin-U, Ultralente U, Novolin ge Ultralente
This insulin (like an intermediate acting insulin) is also commonly mixed with a short-acting insulin. The onset is 4-6 hours with a peak at 8-20 hours. This insulin is taken SC only and administered 30-60 prior to eating.

Combination Insulin
Common trade names: Humulin x/y, Novolin x/y.
CAN x=short-acting insulin and y=intermediate acting (AME list opposite so if 70/30 the insulin contains 70 U of an intermediate-acting and 30 U of a short-acting insulin)
Combination insulin’s combine a short-acting insulin and an intermediate-acting insulin together to provide a nice peak and valley type set up with insulin ultimately controlling blood glucose levels through to about 6-8 hours after administration.

Injection Sites
The most common type of insulin used now is Human insulin. There is some discrepancy as to whether or not rotating injection sites is necessary. The current accepted practice is when using Human insulin rotating sites is not required as human insulin does not cause lipodistrophy as the synthetic and animal insulin’s do. Absorption is consistent if sites are not rotated so controlling blood glucose levels may be easier if only one site is used.

Common injection sites include the abdomen (2 inches out from the umbilicus), the back of the arms, the flank, and the thighs.

Side effects
With the administration of insulin hypoglycemia is the most common side effect that occurs. Hypoglycemia will manifest itself with anxiety; chills; cold sweats; confusion; cool, pale skin; concentration difficulties; drowsiness; polyphagia; headache; irritability; nausea; tachycardia; shakiness; unusual tiredness or weakness.
The Symogyi or rebound hyperglycemia will manifest with drowsiness; flushed, dry skin; fruit-like breath; polyuria; anorexia; tiredness; polydispia.

Log in or register to write something here or to contact authors.