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From Malaga, Spain:

I have a daughter, 8 years old, with diabetes

  1. Is there any statistical survey or data to determine if the use of pre-mixed insulins with pens makes any difference in the blood sugar control in comparison with the self-mixed insulins?
  2. Is it the same to inject 10 units of Mixtard 20 as compared to injecting a self-mixed with 2 units of Actrapid and 8 units of NPH Insulatard?
  3. Is it the same in the case you would produce two simultaneous injections, one with 2 units of Actrapid and the other syringe with 8 units of NPH?


  1. I am not aware of the statistical information but it has been my experience that blood sugars are easier to manage with life's uncertainties when a varying amount of short-acting insulin is given to match food at meals and a longer-acting insulin is given to maintain background insulin needs. When a pre-mixed insulin is given, you lose the flexibility of changing the time of the next meal and the amount eaten without risking a low or high blood sugar. If you adjust the dose of a pre-mixed insulin, you impact the amount of insulin given for at least the next 12 hours. For some people, this does not work well.
  2. If the Mixtard 20 is mixed thoroughly, you are giving 2 units short acting insulin and 8 units longer acting insulin with each injection. This would be comparable to mixing your own. However, what if your daughter's blood sugar was high or low at the time of injection and you wished to add or subtract from the Actrapid amount? With the pre-mixed insulin this would be impossible without impacting the amount of insulin she would have for the rest of the day. Mixing your own gives you more flexibility to adapt to her current insulin needs.
  3. If you would give 2 injections, one of short-acting insulin and one with longer-acting insulin, you might notice that they work more quickly as smaller amounts of insulin are likely to be absorbed easier and quicker than larger amounts. This may mean the dose would be decreased, all based on your daughter's blood sugar response.

I want to commend you for seeking the answers to the best management possible for your daughter. We know through research that, for most people, successful diabetes management needs to be flexible and match the persons life. Learning the skills to do this will make it easier for both of you.


Original posting 13 Aug 1999
Posted to Insulin


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Last Updated: Tuesday April 06, 2010 15:09:06
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