Where Insulin Comes From
Almost all of the insulin sold in the United States today is what is known as "human insulin." Developed by scientists, this laboratory-created insulin is made by DNA recombinant technology and is very similar, really identical, to insulin from a human pancreas. It's available in varieties that are designed to start working within just a few minutes or last for many hours, giving insulin users a lot of control over their blood sugar levels. (Before the introduction of human insulins, people used insulin from beef and pork sources.)
Insulin can't be taken as a pill or capsule because the digestive juices in the stomach ruin its effectiveness. Oral insulin pills might be a reality someday, but right now the only way to take insulin is by injecting it directly into the layer of fat just below the skin. Most people inject insulin with a syringe or insulin pen, although other methods are available.
Basal and Bolus Insulins
The pancreas naturally secretes insulin in two different ways:
While people with type 1 diabetes need a treatment program that gives them both basal and bolus insulin, the treatment for people with type 2 varies and usually changes over time:
Injections of rapid-acting and short-acting insulins provide the bolus insulin supply needed after meals. Conversely, injections of intermediate-acting and long-acting insulin mimic the body's natural basal supply.