Insulin plays a significant role in managing diabetes, a condition where the body either does not produce enough insulin or cannot effectively use it. Precise administration is important for maintaining stable blood sugar levels and preventing complications. For individuals requiring more than one insulin type, mixing them in a single syringe offers convenience and can improve blood sugar management. Understanding the correct mixing procedure is important for patient safety and treatment effectiveness.
Key Insulin Categories for Mixing
Two common types of insulin that are often mixed are Regular insulin and NPH insulin. Regular insulin is a short-acting insulin, appearing as a clear solution. It typically begins to work within 30 minutes to one hour after injection, reaches its peak effect in two to four hours, and lasts for about six to eight hours. Regular insulin is often administered before meals to help manage post-meal blood sugar spikes.
NPH insulin, also known as isophane insulin, is an intermediate-acting insulin that appears cloudy. Its cloudy appearance is due to the presence of protamine, a protein that slows down the absorption of insulin, giving it a longer duration of action. NPH insulin usually starts working within one to three hours, peaks around six to eight hours, and can last for 12 to 16 hours. It provides a more sustained insulin effect, helping to control blood sugar levels between meals and overnight.
The Correct Drawing Order
When mixing Regular (clear) and NPH (cloudy) insulin in a single syringe, a specific drawing order must be followed. The established rule is to always draw up the clear insulin before the cloudy insulin.
A simple way to remember this sequence is the mnemonic “RN,” standing for Regular before NPH. Another helpful phrase is “clear before cloudy.”
Importance of Drawing Order
The specific drawing order of clear before cloudy insulin is important due to the unique properties of NPH insulin. NPH insulin contains protamine, a protein that helps slow its absorption from the injection site. If NPH insulin were drawn first, even a small amount could inadvertently contaminate the vial of Regular insulin.
This contamination could introduce protamine into the clear Regular insulin vial. The protamine might then bind with the Regular insulin, altering its rapid-acting properties. This interaction could delay the onset of Regular insulin’s action or make its effects unpredictable, leading to inconsistent blood sugar control. Unpredictable blood sugar levels can result in either dangerously high blood sugar (hyperglycemia) or unexpected low blood sugar (hypoglycemia), which can have significant health consequences.
Steps for Safe Insulin Drawing
- Gather your Regular and NPH insulin vials, an insulin syringe, and alcohol swabs. Gently roll the NPH (cloudy) insulin vial between your hands to ensure the insulin is evenly mixed, as it can naturally separate. Do not shake the vial, as this can create air bubbles that may affect accurate dosing.
- Clean the rubber stoppers of both insulin vials thoroughly with alcohol swabs. Draw air into the syringe equal to the amount of NPH insulin you need and inject this air into the NPH vial without letting the needle touch the insulin solution. Remove the syringe.
- Draw air into the syringe equal to the amount of Regular insulin needed and inject this air into the Regular (clear) insulin vial. With the needle still in the Regular vial, invert the vial and withdraw the prescribed dose of Regular insulin. Carefully check for any air bubbles and tap gently to remove them, pushing them back into the vial if present.
- Insert the syringe into the NPH vial, invert it, and withdraw the prescribed dose of NPH insulin. Be careful not to inject any of the clear insulin already in the syringe back into the NPH vial. Double-check the total dosage in the syringe before administration; if too much insulin is drawn, discard the syringe and start the process over to ensure accuracy.