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Drug Facts: Premixed Insulin

Updated: Mar 25, 2022

premixed insulin title picture with various pills

Premixed insulin is a product that contains two different kinds of insulin, basal and bolus, all in one injection. It comes premixed and ready to go in either a vial or insulin pen. This means that all of your insulin needs will be met with just one product. Some people find this convenient as there is just one medication to pick up at the pharmacy, which also means just one copay.


Definitions To Help You Out:

  • Basal insulin- “background” insulin which controls blood sugars all day long, particularly between meals and while you are sleeping; can either be long-acting, ultra-long-acting or intermediate-acting; see more info here

  • Bolus insulin- “mealtime” or “prandial” insulin which covers blood sugar spikes after eating; can be either rapid-acting or short-acting; see more info here


Premixed insulin is generally injected twice a day, usually before breakfast and dinner. The length of time it should be taken before meals depends on the product, but most of them recommend taking it 15 minutes prior to the meal.

Although it’s convenient, and injected less frequently when compared to using separate basal and bolus insulins, premixed insulin is not ideal for most people. Because there are two different types of insulin doing different things at different times, things can get quite confusing. With this type of regimen, you’re potentially being set up for more high and low blood sugars. The basal insulin used for all of these premixed products is intermediate-acting which is not ideal either. Intermediate-acting insulin is more likely to cause hypoglycemia (low blood sugar) compared to long-acting insulin and ultra-long-acting insulin.

Another downside of premixed insulin is that if you want to change the dose of one kind of insulin, you’re going to change the dose of the other one as well. Premixed insulin comes in ratios of either 75/25, 70/30 or 50/50, with the larger number being the amount of intermediate-acting (basal) insulin, and the small number being the amount of either rapid-acting or short-acting (bolus) insulin. If 60/40 is the magic ratio that works for you, that’s just not possible. Also, if you’re having a very high carbohydrate meal, you can’t really take more of the bolus insulin to cover it. If you do, then you’ll also take more of the basal insulin which could potentially make your blood sugars too low later that day.

For some people, however, these products may be a good fit. Premixed insulin seems to be used more with older patients. This makes sense as regular meal timing is important with premixed insulin, and stereotypically seniors have more structured meals. Also, if there are vision or dexterity issues, these products may be of value. Some people can have a family member or aid come help them with injections twice daily, but that may not be possible or realistic 3 or 4 times a day.

Premixed insulin can be used in combination with oral medications or non-insulin injectable medications. Potential side effects for all insulins include weight gain and hypoglycemia.



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