Each type of insulin has its own unique behavior. One difference among types of insulin is how long they take to start working at lowering blood-glucose levels. The “insulin peak” is the point at which the dose is working at its maximum, and the “duration” is how long the blood-glucose-lowering effect of the injection will last. The following is a list of insulin types available in the United States, along with how soon they start working, their peak, and how long they last. Talk to your healthcare provider about your insulin regimen.