What to Do If You Miss a Dose of Insulin

What to Do If You Miss an Insulin Dose

Dr. Edelman,

I’m embarrassed to say there have been a few times when I’ve forgotten to take my basal insulin in the morning, as well as my mealtime insulin at dinner. What should I do if I miss a dose again in the future, in either situation?

Dr. Edelman: Let me first say, this happens to all of us taking insulin injections. When it happens, it can mess up our control temporarily and cause added stress! I’m going to address your question in two parts: 1) what to do when you forget your long-acting basal insulin dose, and 2) what to do when you forget your pre-meal “bolus” insulin.

What to Do When You Forget a Basal Insulin Dose

Typically, most people take their basal insulin (Lantus, Tresiba, Toujeo, Levemir, NPH) either in the morning or at night. Some folks split their basal and take some of it in the morning and the rest at bedtime. If you are on a once-daily basil insulin regimen and you remember that you forgot your dose of insulin and you are within 3 or 4 hours of your normal time, you can go ahead and take it late.

If you are on once-daily basal insulin and you are past that 3-4 hour window, then give half of your normal dose and continue the full regular dose at the next regularly scheduled time. You obviously need to keep a close eye on your glucose values in case your numbers creep up too high or drop down too low.

If you are on a split basal (two injections per day) regimen, then I recommend just watching your glucose closely up until your next dose and continue normally. In essence, you would be doing without that basal dose so you may need to give yourself a small correction dose (or doses) of your mealtime insulin up until the next dose. Having a CGM will help you decide if you need any correction doses, and if you do not wear a CGM then you should do more frequent glucose testing with your meter.

What to Do When You Forget a Mealtime Insulin Dose

What happens if you forget to take your mealtime (bolus) insulin? Well, if it’s immediately after you finished eating just take it, but remember that taking fast-acting insulin after eating can cause you to get low later in the day, as the peak action of the insulin will be after most of the nutrients you ate are absorbed. This is the reason why we suggest taking your pre-meal fast-acting insulin at least 20 minutes before you start to eat.

If it’s several hours after eating when you remember you forgot your dose (probably because your glucose value is through the roof) just take a correction dose right away. A correction dose is the amount of insulin that will drop you enough to get in the near-normal range. For example, if your glucose value is 300mg/dL and your correction factor (CF) or insulin sensitivity factor (ISF) is 1:50 mg/dL (meaning that your glucose value will drop 50 mg/dL for every unit of fast-acting insulin), you would give yourself 4 units to get close to 100mg/dL.

However, if you are wearing a CGM and your glucose value is 300mg/dL with a trend arrow going up, then you should give yourself more than the 4 units depending on your individual needs, but at least 2 to 3 units more than your calculation.

Please check out the lectures in our video vault that cover these topics of using the trend arrows to adjust your dose of fast-acting insulin. OMG…I forgot to eat my double-bacon chili cheeseburger…got to run!


Additional Resources:

How Do I Know How Much Insulin I Need with Each Meal?

Trend Arrows and How to React to Them




  1. Avatar

    I forgot to take my insulin,Basaglar before I ate what do I do?

    • Avatar

      Hi Josephine,
      Dr. Edelman gives several options for different scenarios in the article above, but if you are concerned about an immediate situation, please reach out to your doctor.

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