All insulin regimens are made up of some combination of these different types of insulin. Some people can effectively manage their blood glucose levels with one or two injections of premixed insulin per day. These people must inject at specific times of the day, and also eat their meals at specific times. The shorter-acting insulin covers mealtimes and the longer-acting insulin maintains a steady amount of insulin in the bloodstream between meals. Some people with Type 2 diabetes manage their blood glucose levels by combining diabetes pills with one injection of longer-acting insulin in the evening or at bedtime.
Other people inject insulin several times a day, a practice that allows greater flexibility in the timing of their meals. Multiple injection regimens generally involve taking a shot of short-acting insulin before each meal, in combination with one or two injections of longer-acting insulin in the morning or at bedtime. When Regular insulin is injected before meals, a person must wait 30 to 60 minutes before eating. When lispro is used, no waiting is generally required before eating.
As an alternative to multiple injections, some people control their blood glucose with an insulin pump, which infuses insulin around the clock, just like a healthy pancreas, and allows a person to give extra insulin at meals.
For a more in-depth look at insulin, see our article “Understanding Insulin.”