Insulin, a hormone produced by the pancreas, plays a central role in regulating blood sugar levels by helping the body’s cells absorb glucose for energy. Many individuals with diabetes rely on manufactured insulin to manage their condition. A common question that arises for those managing diabetes is whether different types of insulin can be combined in a single injection. Understanding the nuances of insulin mixing is important for effective diabetes management.
Understanding Insulin Types
Insulin preparations are categorized by how quickly they act and how long their effects last within the body. Rapid-acting insulins, such as insulin aspart or lispro, begin working within 15 minutes, peak in 1-2 hours, and last for 2-4 hours. Short-acting insulins, often called regular insulin, typically take effect within 30 minutes, peak in 2-3 hours, and remain active for 3-6 hours. Intermediate-acting insulins, like NPH, have a slower onset of 2-4 hours, peak in 4-12 hours, and can last for 12-18 hours. Long-acting insulins, including glargine and detemir, have an onset of 1-2 hours and provide a relatively steady effect for up to 24 hours or longer, typically without a distinct peak.
Clinical Reasons for Mixing Insulin
Healthcare providers may prescribe a regimen involving mixed insulins to optimize blood glucose control throughout the day and night. Combining insulins with different action profiles, such as a rapid-acting insulin with an intermediate-acting insulin, can help manage both mealtime glucose spikes and provide sustained background glucose control. This approach can also simplify the injection schedule for individuals, potentially reducing the total number of daily injections needed. The goal is to create a more physiological insulin release pattern, mimicking the body’s natural response to food and maintaining stable glucose levels between meals and overnight.
Guidelines for Safe Insulin Mixing
When mixing compatible insulins in a single syringe, a specific sequence must be followed to maintain their effectiveness and prevent contamination. Initially, ensure the correct syringe and needle size are used for the prescribed insulin concentration. Before drawing any insulin, gently roll cloudy intermediate-acting insulin vials between the palms to ensure the suspension is uniformly mixed, avoiding vigorous shaking which can create air bubbles.
The standard practice is to draw “clear before cloudy.” First, inject an amount of air equal to the desired dose into the cloudy (intermediate-acting) insulin vial, but do not draw out the insulin yet. Next, inject an amount of air equal to the desired dose into the clear (rapid or short-acting) insulin vial and then immediately draw the precise dose of clear insulin into the syringe. Finally, insert the needle into the cloudy insulin vial and carefully draw the exact dose of cloudy insulin into the syringe, ensuring no clear insulin is pushed back into the cloudy vial.
This order prevents the clear, fast-acting insulin from being contaminated by the proteins in the cloudy insulin, which could alter its rapid action. If an incorrect amount is drawn, discard the syringe and restart with a new one.
Situations Where Insulin Should Not Be Mixed
Certain types of insulin should never be mixed due to the risk of altering their intended action profiles and potentially leading to unpredictable effects on blood glucose. Long-acting insulin analogs, such as insulin glargine (Lantus, Basaglar, Toujeo) and insulin detemir (Levemir), are formulated to provide a steady, peakless release of insulin over an extended period. Mixing these insulins with other types, including rapid or short-acting insulins, can destabilize their unique formulations, causing their absorption and duration of action to become erratic. This instability can lead to inconsistent glucose control, increasing the risk of low or high blood sugar. Therefore, long-acting insulins must always be administered as separate injections.
Similarly, pre-mixed insulins, which are already formulated with specific ratios of two different insulin types, should not be further mixed with other insulins. These formulations are designed for convenience and a specific action profile, and adding other insulins would disrupt their balance. Improper mixing can lead to adverse outcomes, making precise administration crucial for patient safety.
The Indispensable Role of Medical Consultation
Insulin therapy, particularly involving the mixing of different types, is a complex aspect of diabetes management that requires professional guidance. Individuals should never attempt to mix insulins or modify their prescribed insulin regimen without explicit instructions from a healthcare professional, such as a doctor or diabetes educator. This article provides general information and is not a substitute for personalized medical advice. A healthcare provider can assess individual needs, determine the appropriate insulin types and dosages, and provide precise instructions on safe mixing techniques.