mixed-insulinPerhaps due to insurance reasons, or to help decrease the amount of insulin injections you take, you find yourself on pre-mixed insulin that you take twice a day, before breakfast and dinner. There are different types of pre-mixed insulin, ones that are mixed with intermediate acting insulin and rapid acting insulin, and those that are mixed between intermediate acting insulin and regular acting insulin. These tend to be more affordable. 

Some examples of rapid acting/intermediate acting are Novolog 70/30 (70% intermediate acting, and 30% rapid acting); Humalog 75/25  (75% intermediate acting and 25% rapid acting); and Humalog 50/50 (50% intermediate acting and 50% rapid acting). These insulins have onset times of about 10-15 minutes. Their peak times vary--usually in 4-5 hours--and lasts for about 10-16 hours.

Examples of intermediate acting insulin and regular acting mixes include: Humulin 70/30 ( 70% NPH insulin and 30% regular acting insulin); Novolin 70/30 (70% NPH and 30% regular acting insulin; and Humulin 50/50 (50% NPH and 50% regular acting insulin). The onset for these insulin is longer (30- 60 minutes). Their peak times vary, but usually happen in 4-5 hours, and can last anywhere from 10-16 hours. 

When taking pre-mixed insulin, you need to remember there is no room for flexibility. People who are in a regular routine when taking their medication and have a routine eating pattern, like eat three meals per day at specific times, will be the best candidates for pre-mixed insulin. Because the insulin has certain peak times, it is not flexible like a multi-dose insulin regimen would be.

People on pre-mixed insulin need to eat breakfast, lunch and dinner, and a small nighttime snack. They cannot skip meals and they cannot miss insulin doses. Remember pre-mixed is mixed, so if you skip a dose because you skip a meal you are not only missing your meal time dose but you are missing the background insulin dose for the next 10-16 hours. 

The insulin dose you take at breakfast is peaking 4-5 hours after taking it, so you need to eat 4-5 hours after taking it. If you eat breakfast at 8 am you need to have lunch by 12-1 pm. If you tend to skip lunch or eat at all different times, you will be at risk for going too low, because the morning injection you took is working also over lunch. It is also advised to have a small nighttime snack before bed when on pre-mixed insulin because the dose you take at dinner will be peaking over night or at bed time. 

Signs of hypoglycemia include shaking, dizziness, sweating, hunger, irritability. If you have these symptoms check your glucose. If your glucose is below 80mg/dl, you need to eat 15 grams of carbohydrates, such as 4 glucose tabs, ½ cup of juice or ½ can of soda-regular not diet. Wait 15 minutes and recheck your glucose. Once it is above 100, have your meal or have a high protein bar, or glass of milk with some crackers and slices of cheese. 

So while pre-mixed insulin is less injections, if you tend to forget your insulin, you are not only missing your mealtime insulin but also the background insulin. And skipping insulin frequently will cause your glucose to rise, leading to a more elevated A1c.

If you are looking for more flexibility with your insulin requirements,  a multi-dose regimen consisting of an injection with each meal and one injection at bed might be something to discuss with your healthcare provider. It is more injections per day; however, you may find it allows more room for freedom. No matter what insulin regimen you are on, the only way to see if it is benefiting you is by checking your glucose levels and bringing those glucose logs to your next appointment.