The primary concept when mixing insulin products is to draw up the short acting insulin first and add the longer-acting product to it. This avoids any cross contamination of the short-acting insulin with the long-acting preparation. Contamination of the long-acting with shorter acting insulin is irrelevant. The following steps should be followed when mixing long-acting insulins with short-acting insulin.

• Inspect vials for contamination or degradation.
• Wash hands with soap and water.
• Verify insulin source, strength, insulin syringe size as correct
• Agitate cloudy insulins (NPH in this case) by rolling between palms. New vials may require extensive agitation to loosen bottom sediment. Regular insulin does not require agitation. Bubbles or foam may be formed if vials are shaken. Do not use any vial until all bubbles or foam have cleared.
• Prep vials using sterile technique (alcohol pad)
• Pull plunger of a clean syringe back to prescribed number of long-acting insulin units
• With the long-acting insulin vial resting upright on a flat surface, aseptically, inject the air volume equal to the long-acting insulin dose into the vial and withdraw the needle.
• Repeat the air injection process with the short-acting insulin, inverting the vial and withdrawing the appropriate number of insulin units. Prior to removing the syringe, inspect for bubbles. If bubbles are present, reinject the air into the vial and withdraw the appropriate dose. Withdraw the syringe.
• Invert the long-acting insulin vial, insert the syringe, withdraw the appropriate number of insulin units and remove the syringe from the vial.
• Draw an air bubble into the syringe, invert to mix the insulin within the syringe.
• Expel the air bubbles (recap if prep is for future use or use for infection).