Medicine & USMLE

Short Acting Insulin

Anti-Diabetic Drugs
  1. Insulin Overview
  2. Rapid Acting Insulin
  3. Short Acting Insulin
  4. Intermediate Acting Insulin
  5. Long Acting Insulin
  6. Metformin
  7. Sulfonylureas
  8. Canagliflozin
  9. Pioglitazone


Short-acting insulin formulations include regular insulin. As a short acting insulin, regular insulin works slower than rapid-acting insulins but faster than intermediate acting insulins, with a peak around 2 hours after subcutaneous administration. Importantly, regular insulin is special because it is the only type of insulin that can be given through an IV line. Regular insulin has a clear appearance, and when mixed in a syringe with intermediate-acting insulins, the regular insulin should be drawn up in the syringe first.

Key Points

  • Short Acting Insulin
    • Drug Names
      • Regular Insulin (Humulin R, Novolin R)
    • Onset, Peak, Duration
      • Onset = 30 minutes - 1 hour
      • Peak = ~2 hours
        • Exact peak depends on patient and ranges from 2-5 hours
      • Duration = 5-8 hours
    • Nursing Considerations
      • The only insulin administered via IV
      • Clear” in appearance
      • When mixing with NPH, draw Regular insulin FIRST
        • Clear before cloudy, or “RN” - regular before NPH