Insulin is a hormone, a "chemical messenger" in the body. Insulin is produced in the pancreas. It is needed to allow sugars (glucose) from food to enter cells. There, sugar is used to produce the energy needed for the cells to work properly.
Where does injectable insulin come from?
At first, pancreases from cows and pigs were used produce insulin. In some parts of the world, pork insulin is still on the market. However, since 1983, a product called biosynthetic human insulin has been available. This insulin does not come from human pancreases; it is produced in a laboratory by introducing a synthetic (man-made) human gene into bacteria or yeast. This process produces insulin that is exactly the same as that created in the human pancreas.
Through further changes, people can now prepare different insulins (called insulin analogs) with different action times. Today, all children and nearly all adults with diabetes now receive human insulin products and insulin analogs.
How does insulin act in the body?
Insulins are generally described as:
- rapid-acting (also referred to as fast-acting)
- short-acting
- intermediate-acting
- long-acting
Insulins are also described according to their course of action:
- Onset is the time it takes for the insulin to start working.
- Peak describes the period when the insulin is working at its strongest.
- Duration describes the length of time before the effect of the dose wears off.
Insulin’s effect: how soon, how long
|
Rapid-acting
(lispro/Humalog, aspart/NovoRapid/Novolog) |
Clear |
5 to 10 min. |
½ to 2 hours |
3 to 4 hours |
|
Short-acting
(regular/Humulin R, Iletin II Regular, Novolin-Toronto Buffered) |
Clear |
½ to 1 hour |
2 to 5 hours |
6 to 8 hours |
|
Intermediate-acting
(NPH/Humulin N, Novolin N) |
Cloudy |
1 to 2½ hours |
6 to 15 hours |
18 to 24 hours |
|
Slow or long-acting
(glargine/Lantus, detemir/Levemir) |
Clear |
2 to 4 hours |
Minimal peak |
18 to 36 hours |
|
These times represent averages for each preparation. They may vary from person to person, from one injection site to another, and to some extent in the same person from day to day. |
Premixed insulin
Insulin is available in premixed doses that combine a rapid or a short acting insulin with an intermediate acting insulin in fixed proportions. The name of the preparation indicates the proportions of the different types of insulin (such as 30/70 or 50/50). Premixed insulin is generally not recommended for children.
|
Humalog Mix 25 |
25% rapid-acting, 75% intermediate-acting |
|
NovoMix 30 |
30% rapid-acting, 70% intermediate-acting |
|
Humalog Mix 50 |
50% rapid-acting, 50% intermediate-acting |
|
Humulin 30/70, Novolin 30/70 |
30% short-acting, 70% intermediate-acting |
|
Novolin 40/60 |
40% short-acting, 60% intermediate-acting |
|
Novolin 50/50 |
50% short-acting, 50% intermediate-acting |
Premixed insulin may seem more convenient than mixing your own insulin or giving two injections with insulin pens. However, premixed insulin does not allow for any flexibility. With children, the need for rapid- or short-acting insulin changes on a daily basis, depending on the blood sugar level at the time, and the overall insulin dose requires frequent change with growth and varying appetite and activity levels. Families should be able to alter doses of intermediate and rapid-acting insulins, independent of each other. Premixes don’t allow for this.
Insulin strength and packaging
In North America, insulin is produced at a concentration of 100 units/1 mL. It is available in three ways:
- bottles to be used with needles (syringes); each bottle of insulin holds 10 mL (1000 units)
- cartridges used with insulin pen injectors or continuous pumps; pen cartridges are usually 3 mL (300 units)
- preloaded disposable pens for certain types of insulin only
Who makes insulin?
Eli Lilly, Novo Nordisk, and Sanofi-Aventis are the major manufacturers of insulin in North America.