Forgot to take my Basal!

Forgot to take my Basal!

Section: Insulin
By: Judy Kohn, RN, BSN, CDE

What should I do if I forget my bedtime dose of Lantus®, and don’t realize it until the next morning? I take Humalog® with each meal and Lantus at bedtime. I was so embarrassed to call my doctor and admit I forgot my shot—so I just took the full dose in the morning, but then I got low during the day!

First of all, although I’m not advocating forgetting shots, I do want to say it seems that forgetting a shot is a “rite of passage” with diabetes – i.e. the diabetes is no longer so prominent in your mind that it is monopolizing your every thought-which is a good thing. When patients would call me apologizing for this, I would encourage them to not be too hard on themselves, but rather to just learn from the error, and develop a habit that will prevent them from forgetting shots in the future.

That said, I must first emphasize that the answer to your question must be provided by your healthcare team. Giving specific insulin dosage advice is beyond the scope of this website service. I will explain the principles involved in making the decision on the dose, but it is important that you discuss this with your healthcare professional (HCP).

What You Learned From Your Experience:

  • Don’t panic.
  • Knowing the principles of insulin action will help you understand what to do.
  • You run the risk of getting hypoglycemia if you take the full insulin dose several hours too late, since this new dose will overlap with the other insulin doses circulating in your system.

Insulin Principles:

  • Unfortunately, although HCPs involved with diabetes usually understand insulin adjustment principles, it is difficult to find this advice in published form. Learning how to adjust insulin requires not only an understanding of diabetes but also a lot of practice and experience-and most importantly, knowing the individual person’s specific response to insulin. That is why it is crucial that you discuss all this with your HCP.
  • Commonly, if the shot is only 1-2 hours late, you can usually take your standard dose. But this would depend on other factors: Were you more active than usual? Did you eat less? Are you staying up much later than usual, and will not get the normal amount of sleep? Any of the above circumstances could lower your glucose so you might decide that the dose needs to be decreased somewhat.
  • A general rule is that if the shot is 3 or more hours late, you will need to reduce your dose, since you “missed” those hours -i.e. your body washed out some of that glucose because insulin was not available to help the glucose get into your cells. In other words, you “missed your chance” with that dose and you need to take less insulin.
  • In your situation, you missed a bedtime shot of Lantus, which has approximately a 24-hour action and is intended to provide you with background/basal insulin between meals and during the night. Since you didn’t realize this until morning, you already missed probably 8 or more hours of that dose. Then, taking the full dose in the morning– which was not your usual time-combined with your mealtime Humalog, which gave you too much “insulin on board” during the day-more than you were used to.
  • One option would have been to have you take ½ your usual dose of Lantus that morning, since you already “slept through and missed” 1/3 to 1/2 of the dose. Then, that evening, you would be able to resume your usual Lantus dose. Please note that although this is a principle used by some HCPs, it is very individual and must be discussed with your HCP.


  • Forgetting a shot is human-so please don’t feel embarrassed about this. I’m sure your HCP would prefer you call for assistance so you can prevent a problem rather than wait until it becomes more serious.
  • Decisions on how to adjust a missed dose of insulin vary depending on the type of insulin, the dose, your individual response, how many hours have transpired, and your total insulin regimen for the day. For example, the principles are different for those who take intermediate or long-acting insulin twice a day, or use an insulin pump.
  • You must obtain insulin adjustment advice from your HCP, since each situation is different, and individual needs vary.


This is a common concern. It sounds easy to take medicine at the same time every day, but it can be challenging.

Why is it so important to take it at the same time every day? Insulin glargine (Lantus) is a time-release basal insulin. It works very very slowly. In order to have a stable amount of basal insulin, we must rely on a “carryover” of the previous dose and the new dose. If the new dose is taken more than one hour before or after the previous dose, the basal insulin level can be too low or too high. This will contribute to fluctuating blood glucose levels at all times of the day – not just when the new dose is taken.

Therefore – don’t think it’s hopeless – try to think of a time of day when the insulin glargine (Lantus) will be less likely to be forgotten, or when your daughter is always home. Many parents assume control of the insulin glargine dose for teens – and pick a time of day they are always with their teen and give it to them. It’s one less diabetes task the teen has to remember, and the priority for teens is that they know what to do for diabetes care – and do it – when they are away from home.

Insulin glargine can be taken at any time of the day or night, as long as it is the same time every day. If your daughter wants to keep her insulin glargine time in the evening – then she needs to take it with her if she is likely to be away from home when it is due. Encourage her to ask a friend to remind her, or to set the alarm on her cell phone to remind her. Now that insulin glargine can be given with an insulin pen, it is easier to carry it when out.

If a person forgets to take insulin glargine, and it is 4 or 6 or 8 or 10 hours later – there is no ideal method for getting back on track. Listed below is one approach – but keep in mind – no approach works as well as taking it on time! Until you are back to your usual time for insulin glargine, test blood glucose levels more often – every 3-4 hours, even during the night – and do high blood glucose corrections if above 150 mg/dl.

1. If it is less than 6 hours since the insulin glargine dose was due – take the normal dose of insulin glargine. Also test your blood glucose level – you are likely to be high, so take a blood glucose correction dose if needed. Then over the next few days – gradually move the time of the insulin glargine dose back to it’s normal time, one hour per day. For example – if you normally take insulin glargine at 8pm, but take it at 11 pm because you forgot it. Then the next night take it at 10 pm, then the next night take it at 9pm, etc. until you are back to your original time.

2. If it is more than 6 hours since the insulin glargine dose was due, it is better to skip the insulin glargine injection until the next day. Since you still need to have basal insulin – you will take ultra-short-acting insulin (insulin lispro/Humalog, insulin aspart/Novolog, insulin glylysine/Apidra) every 3-4 hours or short-acting insulin (regular insulin/Humulin or Novolin) to make up the basal insulin.

To figure out how much rapid-acting insulin to take – take your insulin glargine dose and divide it by 24. This equals how much basal insulin you need every hour. Multiply that number by 3, 4 or 6 to determine how much rapid-acting insulin you need to take every 3, 4 or 6 hours for basal only.  Remember: This insulin is IN ADDITION to insulin needed for carbohydrates and to correct high blood glucose levels.

For example: If you take 30 units of insulin glargine a day – take 30 divided by 24 = 1.25 units per hour. If you want to take your basal doses every 3 hours – then multiply 1.25 X 3 = 3.75 units every 3 hours. If you want to take your basal doses every 4 hours – then multiply 1.25 x 4 = 5 units every 4 hours. **Remember to add this insulin to your doses for carbohydrates and high blood glucose corrections. Add all doses together before rounding off.

If forgetting the insulin glargine injection continues to be a problem – encourage your daughter to consider an insulin pump. With an insulin pump – your insulin is always with you, and you don’t take insulin glargine. So you don’t have to do anything at the same time every day.

Related Resources:

Children with diabetes


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