Short-Acting Insulin

Regular (aka Human) insulin is synthetically produced by DNA recombinant technology and is an exact copy of human insulin without amino-acid substitutions.

Brand name examples: Humulin-R or Novolin-R

1. Subcutaneous injection:
   • Regular insulin can be used as a bolus insulin as part of a basal/bolus insulin regimen.
   • Its use has largely been supplanted by rapid-acting insulins (discussed in the next chapter)
2. Intravenous (IV) infusion
   • Regular insulin by continuous IV infusion is most commonly used in the inpatient setting to treat diabetic ketoacidosis (DKA) or persistent hyperglycemia not due to diabetes mellitus.
   • Once DKA has resolved, patients are transitioned from a Regular insulin IV drip to a subcutaneous insulin regimen using a combination of long-acting and rapid-acting insulins (if using multiple daily injections) or just rapid-acting insulin (if using an insulin pump).

1. Subcutaneous Injection:
   • Onset of Action: 30 minutes
   • Peak Action: 2-3 hours
   • Duration of Action: 3-6 hours
2. Intravenous (IV) Infusion:
   • Elimination half-life: ~3-7 minutes
     • Due to this short half-life, stopping an insulin drip will lead to >75% of the Regular insulin being eliminated from the body within 15 minutes of stopping the drip. For insulin-deficient diabetes patients, this means rebound hyperglycemia and rapid re-development of ketosis can occur if a plan for transition for IV to subcutaneous insulin is not in place.
       • Rapid-acting insulin’s onset of action starts around 10-15 minutes but does not peak until at least 2 hours after administration. Therefore, the continuation of the IV regular insulin drip for 30 minutes AFTER administration of rapid-acting insulin for carbohydrate coverage allows for a sufficient “bridge period” to help ensure rebound hyperglycemia and ketosis does not recur.
       • Here at the Stead Family Children’s Hospital, we usually give long-acting insulin while a patient is on the insulin drip, which helps decrease the risk of rebound hyperglycemia and allows for a shorter bridging period (30 minutes instead of 1-2 hours) before shutting off the IV regular insulin drip.