Onset is the length of time before insulin reaches the bloodstream and begins lowering blood glucose. Insulins with long onset (2 to 4 hours) are typically the insulins, or those that have long duration. Those insulins with the shortest onset times (30 minutes) belong to the category, or those with relatively short duration. The insulins have a 1-2 hour onset with 8-12 hours of duration. Among the fast-acting insulins, those based on human insulin, also called Analog insulins, such as Humalog, Novolog, NovoRapid and Apidra, have the fastest onsets. See also peak, duration, and carryover.