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mySugr Bolus Calculator - Get Help With Your Insulin Dose

3/1/2016 by Scott Johnson

mySugr Bolus Calculator - Get Help With Your Insulin Dose

The Insulin Calculator helps you calculate the right amount of insulin or carbs for correction or meals. To make the best use of it, it is important to provide the right settings.

It's time for lunch and your blood sugar is 165 mg/dl (9.2 mmol/L). You have a big slice of pizza, a bag of chips, and a cold Diet Coke waiting for you. How much insulin do you take?

If you wear an insulin pump, you’re probably already using an insulin calculator (they’re often built-in) to inject the correct amount of insulin for correction at mealtimes. You're welcome to continue reading, but there's not much relevant information for you if that's the case.

However, if you’re injecting your insulin (syringes or pens), then stick around. This article will be helpful.

mySugr App download link

What The Heck Is A Bolus?

You probably have a smartphone, right? What does that mean? It means that you should meet mySugr’s Bolus Calculator.

It’s a module integrated into the mySugr app that helps with your insulin dosage. The Bolus Calculator is not yet available in all of the countries where you can download the mySugr Logbook . Please check the availability in your own country. Btw. Bolus Calculators are also known as Insulin Calculators. 

But what the heck is a “bolus,” you ask? Great question. A bolus is a single dose of insulin given all at once. In other words, it’s your mealtime shot or a shot to fix a high blood sugar.

mySugr’s Bolus Calculator makes sense of all the messy numbers involved and suggests a precise dose of insulin.

At mealtimes, it’s super easy. Measure your blood sugar, tell the mySugr Bolus Calculator about your carbs, and let it do the rest. It will even keep track of your active insulin (also called insulin on board or IOB). All you have to do is dial up the dose and take it.

Never heard of active insulin? It’s a concept that helps reduce hypos caused by stacking insulin. We’ll explain this in further detail below.


Getting Started With The Bolus Calculator

Before using the bolus calculator for the first time, you’ll need to enter some details about how your diabetes works. Once you enter all of these settings, you won’t need to mess with them again unless something changes. There are also a bunch of terms and phrases that might be new to you, but don’t worry; we’ll explain everything.


Accessing Bolus Calculator Settings

You can find and adjust any of the bolus calculator  settings in the menu. Use the “Profile & Settings” menu option, then the “Insulin Therapy” field and you’ll see the “Bolus Calculator Settings”.


Step 1: Set Up The Basics 


The mySugr Bolus Calculator only works with rapid-acting bolus insulins. You’ll find a list of compatible insulins in the settings of the mySugr app.

Active Insulin Duration

Now let’s talk about active insulin (also known as insulin on board, or bolus on board).  When you take a dose of insulin, it will affect your blood sugar for multiple hours. It starts working after a short while (about 30-45 minutes later), eventually peaks (around 90 minutes later), and hangs around in your body, continuing to lower your blood sugar for hours. 

The overall time that your insulin stays active is what we call Active Insulin Duration and is one of the mySugr Bolus Calculator settings.

If you take another dose of insulin before your last dose has stopped working, you’re supposed to do the math to figure out how much of the old insulin remains (still lowering your blood sugar). 

If you don’t, you could be stacking your insulin, or taking more than you need. And what happens when you take more insulin than you need? That’s right: low blood sugars.

Sounds complicated, right? The mySugr Bolus Calculator automatically calculates how much insulin is still active. Therefore it needs to know your personal Insulin Acting Time.


mySugr App therapy menue

How To Find Out Active Insulin Duration

If you don’t know which value to enter for your Active Insulin Duration, you’ll want to check with your doctor. With a little time and patience, you’ll be able to figure it out for yourself. 

The next time you need to fix a mildly high blood sugar, track how long your correction shot (or bolus) continues to lower your blood sugar. This is dependent on your sort of insulin and the amount you take but typically for rapid acting analog insulins this times ranges 3-6 hours.

After you inject your insulin, start measuring your blood sugar every 30 minutes over the few next hours until your blood sugar stops dropping any further. You can repeat this exercise a couple of times to get a good estimate of your Active Insulin Duration.

It’s important to be sure that there’s no remaining active insulin from a previous shot to mess with your experiment. And for safety’s sake, check your results with your doctor.


Do you want to dose your insulin in tenths (0.1), half (0.5) full (1) or double (2.0) units?

It may seem like a silly question to ask, but if you use a syringe with markings for whole units, it might be frustrating to get tenth-of-a-unit suggestions.

Let the Bolus Calculator know how you dose, and it will make sure your recommendations come out just the way you like them.

Step 2: Set Your Carb To Insulin Ratio

The Carb to Insulin Ratio is used by the bolus calculator to calculate the amount of insulin that you need to inject for your meal. Therefore the bolus calculator needs to know the amount of carbs in your meal to provide you with an accurate insulin recommendation.

Set in your ways when it comes to thinking about your insulin at mealtimes? Does, “That’s a four unit sandwich,” and, “I’d need at least ten units for that meal,” sound familiar? 

But we need to do the work from the opposite direction to uncover a piece of the equation. 

If you’re counting carbs by grams, we need to know how much work a single unit of insulin can do. In other words, how many grams of carbs can you eat for one unit of insulin? If you’re counting carbs by exchanges, the mySugr Bolus Calculator will ask you how many units of insulin you take for one exchange.

For example, if you count 15 grams of carbs as one exchange (configured in the settings), and would inject  one unit of insulin for that, then your carb to insulin ratio is 1. 

If you don’t know your carbs to insulin ratio(s), start by talking with your doctor. They can help you find a good starting point, and you can do some testing to fine-tune the settings. 

You might have different ratios at different times of the day, which you can set as needed.


Step 3: Set Your Insulin Correction Factor

The Insulin Correction Factor is used by the mySugr bolus calculator to calculate the amount of insulin that you need to correct high blood sugar values and bring you back to your target value. 

Therefore, the bolus calculator needs to know how much 1 unit of insulin will lower your blood sugar. Again, you might have different factors at different times of the day, which you can set here as needed. 

Remember, if you’re ever unsure, talk with your doctor. They can help you find a good place to start and do some fine-tuning. In fact, it’s easy to test your correction factor while testing your active insulin duration, as described above. 

To do so, you’ll need to track how much a unit of insulin lowers your blood sugar level (Insulin Correction Factor), as well as how long it takes for that unit to stop working in your body (Active Insulin Duration).

As mentioned earlier, it’s smart to repeat this experiment a few times to get an accurate read of the situation. It’s also important to ensure that there’s no old insulin to interfere with the experiments. And again, for safety’s sake, check your results with your doctor.


mySugr insulin calculator settings

4. Setting your blood glucose target value

Your target value is your most comfortable value. This is the blood sugar level that helps you get through the day feeling relaxed. Of course, you can also choose individual target values for different periods of time, for example, a little higher at night than during the day. 

All values above your target value will be corrected to the target value. This means you will receive a recommendation for corrective insulin. As for values that are below your target value, the bolus calculator will give you a recommendation of how many carbs you need to eat to bring you blood glucose value back to your target value.


Accessing Bolus Calculator Settings

You can find and adjust any of these settings through the menu. Use the “Profile & Settings” menu item, then the “Insulin Therapy” field and you’ll see the “Bolus Calculator Settings” field.

How To Use The Bolus Calculator

Once your settings have been saved, using the bolus calculator is very simple. Enter your blood sugar, and/or carbs, then press the calculate button.

Active insulin is really important, so you may be asked to confirm that you haven’t forgotten to log any recent shots (if you’ve logged them, the bolus calculator will automatically include any active insulin in the calculation). 

The 5:00 figure in the confirmation example above is based on the Active Insulin Duration setting. If your Active Insulin Duration setting is something different, you’ll see that instead. Here’s how the two buttons work:

  • Cancel – if you suddenly remember a recent shot that you forgot to log, no problem. Cancel here and add a new entry. In the new entry screen, tap the “Time” field to adjust the timestamp back to when you took that shot (this is the same technique you’d use to do any back entries), enter the appropriate details and save it. Now that you’ve told mySugr about that insulin, you can start your current bolus calculation again (by creating another, current, new entry) and whatever portion of that shot is left (based on your Active Insulin Duration setting) will be included in the calculation.
  • Continue – this confirms that you don’t have any active insulin on board, and you can continue with the bolus calculation.

To continue, tap the mySugr Bolus Calculator button again to accept the suggested insulin dose. You’ll see the units automatically move to the appropriate insulin fields and you can fill in any additional details. 

Save the entry with the green tick (upper right corner) or the save button (bottom of the screen). 

We’ll record everything and start tracking your active insulin for future bolus calculations. There you have it. A precise, personalized insulin dose calculated just for you.


Why Isn’t mySugr’s Bolus Calculator Available In My Country?

The mySugr Bolus Calculator module is a risk class IIb medical device. That’s higher up the regulatory ladder and requires additional review by each individual country’s authorities before we can release it.

Wrapping Up

We hope we’ve provided you with a glimpse of just how easy insulin dosing can be. Figuring out how much insulin to take doesn’t have to be such a pain. 

Let mySugr do the work for you, by calculating your insulin dosage precisely.


This article has been updated in September 2020


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The mySugr website does not provide medical or legal advice. mySugr blog articles are not scientific articles, but intended for informational purposes only.

Medical or nutritional information on the mySugr website is not intended to replace professional medical advice, diagnosis or treatment. Always consult a physician or health care provider with any questions you may have regarding a medical condition.

Scott Johnson

Almost famous for being a Diet Coke fanatic, Scott is the Patient Success Manager, US for mySugr and has lived well with diabetes for over 40 years. He's an active pioneer in the diabetes social media space and along with his work at mySugr, he manages his award-winning blog, when time allows.