What Should I Do AFTER a Low?

How to Avoid a Second Low... Without Over-Treating

Michelle MacPhee, D-Mom

Sometimes after our son treats a low blood sugar, his BG skyrockets soon after. On the flip-side, sometimes his blood sugar comes up to target immediately after the low treatment, only to fall back down again within the hour. Why does that happen? What can we do to reduce the persistent lows and highs?

You've likely been given the standard recommendation for treating low blood sugar: eat 15g of fast-acting carbs, wait 15 minutes, then re-check. In most situations this does the trick and life goes on.

But sometimes that low keeps coming back. Or you spend the rest of the day dealing with high glucose. Like most diabetes-related challenges, it’s difficult to nail down the best approach for preventing extreme blood sugars after low treatment. On the one hand, you want to treat the lows effectively and prevent another low from occurring on the heels of the first. On the other hand, you don’t want to over-treat the low, resulting in highs later (which then require treatment, which may lead to another low, which will then require treatment... round and around we go!)

To reduce the swings to both extremes that occur after a low treatment, here are a few questions that will help you figure out the best way to follow up in different sitautions.

For individual recommendations about any of these strategies, check with your child’s diabetes health care team.

1. What insulin program is your child on?

Conventional using N/NPH? Multiple Daily Injections (MDI)? Insulin Pump?

If it’s a Conventional insulin program (which uses an intermediate-acting insulin, such as N or NPH) this insulin peaks (is strongest) several hours after the insulin is injected. So if the low occurs during peak time, your child will need more than just a low treatment to avoid a blood sugar crater.

Given a Conventional insulin program (N/NPH), if low blood glucose occurs with more than 1 hour until the next meal or snack, the following approach may be effective:

  • Treat the low BG, wait 15 minutes, re-check, then give a snack containing a starch and a protein (for example, crackers and cheese, or ½ of a peanut butter sandwich).
  • In many cases, it may be recommended not to give insulin with this snack (because of the peak in the insulin action). This is particularly true if your child would not normally receive insulin for this snack.

If you deliver your insulin using Multiple Daily Injections, long-acting insulin action is flatter (doesn't come to a sharp peak) so you may not have the same need to feed the insulin. If your child wears an insulin pump, you only need to consider the action profile of fast-acting insulin (see below).

2. How long has it been since the last bolus?

If your child uses a long-acting insulin (such as Lantus®, Levemir®) OR she uses an insulin pump to deliver insulin, then the most recent dose of rapid-acting insulin may be the culprit if your child is having a second (or third) low.

(Note: On MDI or a Pump, the basal (background) insulin could also be having an effect, especially if lows occur commonly at the same time of day, or lows occur more than 2 hours after the most recent bolus.)

In the case of an MDI program (Multiple Daily Injections) OR an insulin Pump program, your follow-up depends on whether it has been less than or more than 2 hours since the last bolus:

If low blood glucose occurs less than 2 hours after the last dose of rapid-acting insulin, the following approach may be effective:

  • Treat the low, wait 15 minutes, re-check, then give a snack containing a starch and a protein.
  • Consider giving this snack without rapid-acting insulin, to help prevent another low. (Note: The closer the low happens to the last bolus, the more “extra carbs” your child may need to prevent another low.)

Tips from the Trenches

We have not found this particular guideline to work for our family. In our experience, when our son’s BG goes low soon after (or during) a meal or snack, it is usually because the pre-bolus time was too long, and/or the meal or snack was low GI. In both cases, the insulin got in before the food did. If we do not give him insulin for this snack, his BG will skyrocket later, when the food is fully digested. So under these circumstances, in our family often we give the usual insulin with the snack that follows the low. Additionally, since our son started using an insulin pump, we have found that a follow-up snack is not necessary for him to prevent another low – we only provide a follow-up snack/meal if one was already planned at that time. But everyone is a little different – as with all guidelines, see what works best for your child.


If our son goes low before 2 hours it’s usually because: 1) he has had a busy day with lots of extra exercise and is more sensitive to insulin, or 2) he has had a low glycemic index meal so the insulin has acted before the food has been digested, or (3) the insulin “pre-bolus” was given too soon before eating, so again, the insulin has acted before the food has been digested. For the first case (1), he needs to have more carbs than the low treatment because essentially he has been given too much insulin. In the second case (2), we give him the low treatment but give insulin for that low treatment after 30 min to 1 hour. The reason is because it’s a timing issue, with the insulin acting much more quickly than the food. By giving insulin for the low treatment, we prevent a high BG later, when the food has been digested. The next time he has that low glycemic food (ex. pasta; really cheesy pizza; high-fat fast food), we will do a combo bolus to slow down how quickly the insulin goes in (before we had a pump, we would give 25-50% of the insulin with the meal and the remainder after 1 ½ hours). For (3), in which we pre-bolused too far in advance, we would give a low treatment with insulin as in (2), and then next time use a shorter pre-bolus time period.


If a low blood glucose occurs more than 2 hours after the last dose of rapid-acting insulin, the following approach may be effective:

  • Treat the low, wait 15 minutes, re-check, then give a snack containing a starch and a protein.
  • Unlike the scenario above, consider giving this snack with rapid-acting insulin (either the usual amount of insulin, or a reduced dose) to prevent a high blood sugar later.

3. Has my child been physically active?

Because exercise affects blood glucose levels, the amount and timing of exercise (that has already happened, or is planned for the immediate future) may influence your follow-up strategy after a low.

If your child has a low blood sugar during exercise:

  • Treat the low and have your child rest for at least 15 minutes before resuming the activity (or until he or she is feeling better).
  • Your child may also need extra carbs for the remaining exercise to prevent another low.

4. Any carbs missed at the last meal or snack?

This has happened to us more often than I’d like to admit! If our son gets distracted during a snack and leaves some food behind (food for which he received insulin), or if we realize that we made a calculation error when we counted the meal carbs, or if we wildly guess at the carb content of a less-familiar food (here I’m thinking of fancy desserts and take-out spring rolls)... this creates a mismatch between the carbs consumed and the insulin dose given.

If your child has a low and you realize in hindsight that she did not eat all of the last meal/snack and yet received the full bolus OR there was a miscalculation of carbs for the last meal/snack (carbs were overestimated, resulting in an insulin dose that was too high):

  • Your child likely needs extra carbs, without insulin.
  • The amount of extra carbs may correspond to the amount of carbs missed during the last meal/snack (which may or may not be more than your child’s usual low treatment).
  • Because the timing of food and insulin is now out of sync , things may not work out perfectly. Monitor your child closely to see if this is the case.

5. Could my child be sick?

Illness messes things up when it comes to diabetes! If your child has thrown up, then there will be too much insulin for the amount of carbs that were digested. In addition, a few days before illness the body may become more or less insulin-sensitive. For example, our son has 2 days of lows before he gets a cold or flu (when he has no other visible symptoms) then persistent highs during his illness.

Extra caution needs to be taken with low prevention around illness, especially if your child is vomiting. If your child has a low blood sugar and he vomited following his last meal/snack:

When in doubt about how to manage diabetes during illness, check with your child’s diabetes health care team.

6. Is the amount of fast-acting sugar appropriate for my child?

For the first several months after our son was diagnosed with type 1 diabetes at just over a year old, his blood glucose consistently went high after a low treatment. We came to realize that for his small and highly carb-sensitive body, the standard low treatment recommendation included too many carbs for his individual needs, effectively resulting in over-treatment of the low. Once we bumped down the amount of carbs he received as a low treatment, many of his post-low highs disappeared.

Also, the amount of fast-acting sugar that worked well to treat a low a few years ago may longer be effective as your child's body grows and changes. You may need to increase the size of low treatments over time.

If you find that your typical low treatment often leads to highs or lows:

  • You may want to add or subtract a few skittles or a quarter cup of orange juice.
  • Be conservative with any changes.
  • Pay attention to the result, and decide what amount of low treatment works best for your child’s individual needs. It may be more than, less than, or the same as the standard recommendation for treating lows.

Some Final Thoughts

There are a variety of factors that can lead to blood glucose swings. While even the most diligent caregiver will find it impossible to perfectly control diabetes, looking more closely at the above factors – insulin program, time since last bolus, exercise, missed carbs, sickness, and size of low treatment – may help reduce the highs and lows that commonly occur after a low blood glucose episode. Try the follow-up strategy that you feel may impact BG swings the most, note the results, and tweak your process according to your child’s individual needs.

All the best to you and your family as you tame the diabetes dragon!