Managing blood sugar levels often involves insulin administration, sometimes by mixing different types of insulin in a single syringe. This technique allows for a combined effect, providing both quick blood sugar control and sustained action throughout the day. Accurate execution of this procedure is essential to ensure insulin effectiveness and patient safety, as deviations can impact its properties and blood glucose management.
Understanding Insulin Types for Mixing
Insulins commonly mixed fall into two main categories, distinguished by their appearance and how quickly they work. Rapid or short-acting insulins, such as Regular insulin (e.g., Humulin R, Novolin R) or rapid-acting analogs like insulin aspart (Novolog) and insulin lispro (Humalog), are clear. These insulins begin working quickly to lower blood sugar after meals and have a short duration of action. Intermediate-acting NPH insulin (e.g., Humulin N, Novolin N) has a cloudy or milky appearance. This cloudy nature is due to protamine and zinc, which slow its absorption and prolong its effect. NPH insulin provides a slower onset and longer duration, used for background blood sugar control.
The “Clear Before Cloudy” Principle
When mixing insulin, always draw the clear insulin into the syringe before the cloudy insulin. This is known as the “clear before cloudy” principle. This order prevents contamination of the clear, short-acting insulin vial with cloudy NPH insulin. If NPH enters the clear insulin vial, it could alter the clear insulin’s rapid-acting properties, potentially slowing its onset. Maintaining purity ensures predictable blood sugar control.
Step-by-Step Guide to Mixing Insulin
Mixing insulin accurately requires a methodical approach. Begin by gathering all necessary supplies: an insulin syringe, both clear and cloudy insulin vials, and alcohol swabs.
Gently roll the cloudy insulin vial between your palms to ensure particles are evenly distributed. Never shake it vigorously, as this can create air bubbles.
Clean the rubber stoppers of both insulin vials thoroughly with an alcohol swab and allow them to air dry.
Draw air into the syringe equal to the dose of the cloudy NPH insulin. Insert the needle into the cloudy NPH vial, inject this air, then withdraw the needle without drawing any insulin.
Draw air into the same syringe equal to the dose of the clear insulin. Insert the needle into the clear insulin vial, inject the air, then invert the vial and syringe to carefully draw up the prescribed dose of clear insulin.
After withdrawing the clear insulin, immediately insert the needle into the cloudy NPH insulin vial, invert it, and draw up the prescribed dose of NPH.
Finally, check the syringe for any air bubbles. Gently tap the barrel to move them to the top, expelling them if present, before administering the injection promptly.
Crucial Safety Precautions
Beyond the drawing order, several safety measures are important when handling insulin. Not all insulin types can be mixed; for example, long-acting insulins like insulin glargine (Lantus, Basaglar, Toujeo) and insulin detemir (Levemir), as well as ultra-long-acting insulin degludec (Tresiba), should never be mixed with other insulins in the same syringe.
Always inspect insulin vials for changes in appearance, such as discoloration, cloudiness in clear insulin, or the presence of lumps or flakes. Before each use, verify the expiration date on both insulin vials.
Unopened insulin should be stored in a refrigerator, typically between 36°F and 46°F (2°C to 8°C), while opened vials can often be kept at room temperature, usually between 59°F and 86°F (15°C and 30°C), for up to 28 days, depending on the manufacturer’s guidelines. Insulin should never be frozen or exposed to extreme heat or direct sunlight, as this can reduce its effectiveness.
Always use a new, sterile syringe for each injection and dispose of used syringes safely in a puncture-resistant container. Consulting a healthcare professional or diabetes educator for personalized instructions and training is always recommended.