Medicine & USMLE

Short Acting Insulin

Diabetes 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. Meglitinides
  9. Thiazolidinediones (TZDs)
  10. DPP-4 Inhibitors
  11. Incretin Mimetics
  12. SGLT2 Inhibitors
  13. Alpha Glucosidase Inhibitors
  14. Pramlintide


Short acting insulin acts fairly quickly to lower blood glucose levels, peaking between 2-4 hours after administration. The only drug name you need to know is regular insulin. Regular insulin is the only insulin that can be given in an IV, making it important in treating diabetic ketoacidosis, or DKA. Diabetics should administer short-acting insulin 30-60 minutes before meals. Finally, if mixing regular insulin and NPH insulin, always be sure to draw regular insulin into your syringe first.

Key Points

  • Short Acting Insulin
    • Drug Names
      • Regular insulin (Humulin R, Novolin R)
    • Onset, Peak, Duration
      • Onset = 30-60 minutes after administration
      • Peak = 2-4 hours after administration
        • Peak time is the most important timing to know, since it’s at the peak that patients are most likely to experience hypoglycemia
      • Duration = 5-8 hours after administration
    • Administration
      • Can be given IV
        • Regular insulin is the only insulin approved to be given through an IV. Other insulins must be given subcutaneously.
        • Treats Diabetic Ketoacidosis (DKA)
          • When regular insulin is given through an IV it works extremely quickly. This makes it ideal for treating diabetic ketoacidosis (DKA), a condition of extremely high blood glucose levels.
      • Give 30-60 minutes before meals
        • Note that this matches the onset of regular insulin. By timing insulin administration 30-60 minutes before eating, the insulin will start having an effect right as the blood glucose levels are starting to rise.
      • When mixing insulin types, draw regular insulin first
        • Regular insulin should be drawn into the syringe FIRST, before NPH insulin
        • “RN” - regular before NPH