Insulin is a natural substance that is produced in the human body by the pancreas. Insulin helps control the use of glucose (sugar) in the body. Insulin is also involved in the processes that break down carbohydrates, fats, and proteins received from the diet into substances the body can use.

Insulins in this Class
Insulin - Mixed (Humalog Mix 75/25, Humulin 50/50, Humulin 70/30, Iletin II Mixed, NovoLog Mix, Novolin 70/30)
Insulin Aspart injection (Novolog)
Insulin Aspart; Insulin Aspart Protamine injection (Novolog 70/30, Novolog Mix 70/30)
Insulin Detemir Injection (Levemir)
Insulin Glargine injection (Lantus)
Insulin Glulisine Injection (Apidra)
Insulin Lispro (Humalog)
Insulin Lispro Protamine Injection (Humalog Mix 50/50)
Insulin inhalation powder (Exubera)
Insulin injection (Humulin, Iletin II, Novolin, Velosulin)
Insulin regular (Humulin R, Novolin R, Regular Iletin II, Regular insulin)

Summarizing the Evidence
Historically, insulin was derived from animal sources, mainly the cow and pig. With advances in medicine over the past few decades, namely recombinant DNA technology, human insulin can now be manufactured or synthesized. Synthetic human insulin is identical to natural insulin that is made in human body and is now the most common form of insulin used.

Various formulations of injectable human insulin are available including regular insulin (R), isophane insulin (NPH), lente insulin (L), and ultralente insulin (U). To decrease the number of injections for those individuals who require more than one kind of insulin, insulins have also been combined into one product. These combined insulin products include 70/30 insulin (comprised of 70% NPH / 30% R), 50/50 insulin (comprised of 50% NPH / 50% R), and Humalog 75/25 insulin (comprised of an insulin lispro mix).

The newest forms of injectable insulin include insulin lispro (Humalog), insulin aspart (Novolog), insulin glargine (Lantus), insulin glulisine (Apidra), and insulin determir (Levemir). These forms of insulin were created in hopes to lessen side effects, improve effectiveness, and have differing onsets, peaks, and duration of activity over the previous human insulin formulations. To see how the various insulins compare with regard to their onset of blood sugar-lowering activity, their peak time of effect, and their duration of effect on blood sugar-lowering, please see the table directly below.

In addition to injectable forms of insulin, in 2006, an inhalable form of insulin was FDA-approved for us. This inhaled insulin is marketed under the name, Exubera. Exubera is a synthetic human inhaled insulin that is a short-acting insulin that starts working faster than injected regular (R) insulin. While inhaled insulin offers an alternative to injectable insulin, inhaled insulin is not for everyone. Some individuals may have difficulty using the inhaler device.