Yes, Humulin R and Humulin N Can Be Mixed Together
Yes, you can safely mix Humulin R (regular human insulin) with Humulin N (NPH insulin) in the same syringe and use them together. This combination is explicitly approved and recommended in clinical practice guidelines.
How to Mix Them Properly
According to FDA labeling and ADA guidelines, when mixing these two insulins 1:
- Draw Humulin R (regular insulin) into the syringe FIRST
- Then draw Humulin N (NPH insulin) second
- Inject immediately after mixing
This order is critical because you want to avoid contaminating the clear regular insulin vial with the cloudy NPH insulin.
Why This Combination Works
The evidence strongly supports this practice 2:
NPH and short-acting (regular) insulin formulations when mixed may be used immediately or stored for future use 2. This is different from other insulin combinations that have compatibility issues.
The pharmacokinetic data shows that while there is a slight decrease in absorption rate when regular insulin is mixed with NPH, the total bioavailability remains unchanged 2. Importantly, clinical trials demonstrate that postprandial blood glucose response is similar whether the insulins are mixed or injected separately 2.
Research confirms this is safe and effective - a study directly comparing mixed Humulin R and Humulin N showed no changes in insulin requirements, HbA1c levels, or hypoglycemia rates 3.
Clinical Application
This combination is commonly used in clinical practice 4:
- Self-mixed/split regimens allow you to adjust NPH and regular insulin doses separately based on individual needs
- Typically given as 2/3 of total dose before breakfast and 1/3 before dinner
- Can reduce the number of daily injections compared to separate administrations
Important Caveats
Do NOT mix NPH with:
- Lente insulins (zinc phosphate precipitation occurs) 2
- Insulin glargine (due to low pH of its diluent) 2
When mixing is contraindicated:
- If using insulin pens (mixing only applies to vial and syringe use)
- If the mixture will not be used immediately (though NPH/regular can be stored after mixing, immediate use is preferred)
The key advantage of this combination is that it provides both mealtime coverage (from regular insulin) and basal coverage (from NPH) with a single injection, improving adherence while maintaining glycemic control equivalent to separate injections.