Insulin mixing involves combining different types of insulin in a single syringe before injection. This practice aims to reduce daily injections and create a more tailored blood sugar control pattern. The decision to mix insulins should always be made in close consultation with a healthcare provider, as it requires careful consideration of individual needs and insulin properties.
Understanding Insulin Types
Insulin medications are categorized by how quickly they act and how long their effects last.
Rapid-acting insulins, such as insulin lispro, aspart, and glulisine, begin to lower blood sugar within 5-15 minutes, peak in 1-2 hours, and last 2-5 hours.
Short-acting insulin, referred to as regular insulin, has a 30-minute onset, peaks in 2-3 hours, and can last up to 8 hours.
Intermediate-acting insulin, NPH insulin, takes 1-3 hours to start working, peaks between 6-8 hours, and provides coverage for 12-16 hours. Understanding these action profiles is important for determining appropriate mixing combinations.
Specific Insulin Combinations for Mixing
Certain insulin types can be safely mixed to provide both immediate and sustained blood sugar control. The most common combination involves short-acting (Regular) insulin with NPH insulin. Rapid-acting insulins, such as insulin lispro (Humalog), insulin aspart (Novolog), and insulin glulisine (Apidra), can also be mixed with NPH insulin. These combinations are permissible because NPH’s formulation helps preserve the rapid action of the other insulin, offering a dual-action effect from a single injection. These mixtures should be administered immediately after preparation to maintain their intended properties.
The Correct Mixing Procedure
Proper technique is essential when mixing insulins to ensure accuracy.
Begin by checking the healthcare provider’s specific order for insulin types and dosages. Wash your hands thoroughly and gather all necessary supplies, including the insulin vials and a new syringe. Gently roll the NPH insulin vial between your palms to evenly mix its cloudy suspension, avoiding vigorous shaking which can create air bubbles. Clean the rubber stoppers of both insulin vials with alcohol swabs and allow them to dry.
To draw the insulin:
First, inject air equal to the dose of NPH insulin into the NPH vial, but do not withdraw any liquid yet.
Then, using the same syringe, inject air equal to the dose of the clear (rapid- or short-acting) insulin into its respective vial.
Without removing the needle from the clear insulin vial, invert it and withdraw the prescribed dose of clear insulin, ensuring no air bubbles are present.
Insert the needle into the NPH vial, invert it, and carefully draw the NPH insulin into the same syringe.
This “clear before cloudy” method prevents contamination of the clear insulin vial with NPH. The combined dose should be injected immediately after mixing to ensure optimal effectiveness.
Insulins Not Suitable for Mixing
Not all insulins are designed to be mixed, and combining incompatible types can lead to unpredictable effects on blood sugar control.
Long-acting insulin analogs, including insulin glargine (Lantus, Toujeo), insulin detemir (Levemir), and insulin degludec (Tresiba), should never be mixed with any other insulin. These insulins are formulated with specific pH levels or molecular structures crucial for their prolonged, steady release. Mixing them can alter their chemical integrity, causing them to precipitate, lose their extended action, or change the absorption rate of the other insulin.
Pre-mixed insulin formulations, which already contain a fixed ratio of different insulin types, should not be mixed with other insulins. These products are manufactured to deliver a precise combination, and further mixing could disrupt their intended action. Incompatible mixing can result in unpredictable blood glucose levels, potentially leading to hyperglycemia (high blood sugar) or an increased risk of hypoglycemia (low blood sugar).
Essential Safety Practices
Adhering to strict safety practices is paramount when managing insulin, especially when mixing different types. Always consult a healthcare provider before attempting to mix insulins, as they provide personalized guidance and ensure the regimen is appropriate for individual health needs.
Maintaining consistency in the mixing routine, including the order of drawing insulin and immediate injection, is crucial for predictable outcomes. Proper storage of insulin vials, both opened and unopened, is important to preserve their potency.
Closely monitoring blood glucose levels is a continuous safety measure, helping to identify any unexpected responses to mixed insulin and allowing for timely adjustments under medical supervision. Be aware of the signs of incorrect mixing or altered insulin effects, such as unusual changes in blood sugar patterns. Never self-adjust insulin doses or mix insulins without medical guidance, and always dispose of used syringes and needles safely in a designated sharps container.