Rapid-acting insulin: Effective within 15 minutes of injection, at approximately 1 hour it will hit its peak efficiency but continues to work for two to four hours. This is normally taken before a meal and in addition to a long-acting insulin.
Short-acting insulin: Effective within 30 minutes after injection, at approximately 2 to 3 hours it will hit its peak efficiency but continue to work for three to six hours. It is usually given before a meal and in addition to a long-acting insulin regimen.
Intermediate-acting insulin: Effective within 2 to 4 hours after injection, at approximately 4 to 12 hours later it will hit its peak efficiency and continues to work for 12-18 hours. It is usually taken twice a day and in addition to a rapid- or short-acting insulin.
Long-acting insulin: Effective several hours after injection and continues to work for approximately 24 hours. If necessary, it is often used in combination with rapid- or short-acting insulin.