Humulin is the brand name for a group of human insulin products, originally developed by Genentech in 1978 (Generic name insulin isophane) and later acquired by Eli Lilly and Company.

Humulin is synthesized in a laboratory strain of Escherichia coli bacteria which has been genetically altered to produce human insulin. The synthesized insulin is then combined with other compounds or types of insulin which affect its shelf life and absorption. Humulin R, for example, consists of zinc-insulin crystals dissolved in a clear fluid.

Humulin by itself is a short-acting insulin. Humulin R, like many other form of injectable insulin, is intended for subcutaneous injection, so it should not be used intramuscularly, since its dispersion in the rest of the body would take more time.

It is currently sold by Eli Lilly under different types:

* Humulin ® R (REGULAR human insulin injection [rDNA origin]) is a short-acting insulin that has a relatively short duration of activity as compared with other insulins.

* Humulin R Regular U-500 (Concentrated) insulin human injection, USP (rDNA Origin) is a stronger concentration (500 units/mL) of Humulin R.

* Humulin N (human NPH insulin injection [rDNA origin]) is an intermediate-acting insulin with a slower onset of action and a longer duration of activity than Humulin R.

* Humulin 70/30 (70% human insulin isophane suspension, 30% human insulin injection [rDNA origin]) is a mixture insulin. It is an intermediate-acting insulin combined with the onset of action of Humulin

* Humulin 50/50 (50% human insulin isophane suspension, 50% human insulin injection [rDNA origin]) is a mixture insulin. It is an intermediate-acting insulin combined with the onset of action of Humulin R.

Based on the company's web site, Humilin is identical in chemical structure to human insulin.