Learn · Bolusing

Bolusing

I bolus every time I eat. If I’m going to do it that often, I should probably be good at it.

Food, insulin, and exercise, and for each one, when and how much.

Before lunch105
Peak152
Back under 1401:23 PM
Time in range100%

Lunch, and a walk afterBolus, eat, walk, back in range.

All in mg/dL. The pink band is my range, 70 to 180, and the darker band is my tight range, 70 to 140. The green stretch is the walk.

Coll. Haley Maddox · Oct 2026Next: Reports →

Just a reminder
My diabetes care is managed in close partnership with my care team. This page shares what works for me. It isn't medical advice. Talk with your own doctor or diabetes care team before you change anything about your care.

Start here

So many things, all at once

Food, insulin, and exercise, but also sleep, stress, being sick, hormones, the heat, and a lot more. Adam Brown counted 42 of them,¹ and people with diabetes talk about that list all the time. With that many things moving at once, it’s hard to tell what caused what.

That’s why it’s easiest to learn when as few things as possible are changing. You won’t eat the same measured breakfast every day for the rest of your life, but doing it for three weeks can teach you how your body responds in the morning. What you learn in those three weeks, you get to use for the rest of your life.

It can feel hard while you’re learning. It isn’t about eating the same way forever, or for every meal. It’s about giving yourself the best chances to learn.

Want the whole story? Adam Brown’s book, Bright Spots & Landmines, free from diaTribe.

42 things that can move my blood sugar Adam Brown, “42 Factors That Affect Blood Glucose”, diaTribe

For bolusing, three matter most

You want to be able to eat anything you want. A little planning makes it easier.

1
Food

WhenIt matters when I’m eating and how fast the food will hit. A pretzel gets a longer pre-bolus than a salad.

How muchI count the carbs as honestly as I can, using the label, a food scale, or a nutrition menu when I eat out. Then I match my insulin to them with my insulin-to-carb ratio.

Counting carbs ↓
2
Insulin

WhenI bolus before I eat, usually about 15 minutes ahead, and closer to the meal if I’m at a lower number. How long it keeps working after depends on the type of insulin.

How muchI take units for the carbs, plus a correction if I’m running high. That adds up to 10 to 25 units a day.

Timing the bolus ↓How insulin works →
3
Exercise

WhenThe past two daysAll my exercise adds up, not just today’s. A long walk yesterday and a day in the garden today both count.Right nowMoving with insulin on board makes it act faster.

How muchMore exercise means each unit does more. After a lot of it, I go by how fast my glucose is changing, not my usual pre-bolus.

When I’m moving ↓

Quick takeaways

If you only read one part, read this.

Pre-bolus. It’s the pillar.
For most meals, my insulin goes in about 15 minutes before I eat. It’s the habit everything else builds on.
After a big workout, it depends on the meal.
A small meal? I eat, wait, and respond. A big one with extra carbs? I probably still bolus for the extra. It really varies.
Set your alerts to your targets.
My alerts sit at the edges of my range, so I hear about a rise while a small, quick fix still works. My alarm settings →

1 · Food

Counting carbs

Carbs turn into sugar in the blood. Before I eat, I count the carbs and match my mealtime insulin to them with my insulin-to-carb ratio, plus a correction if I’m running high. My ratio and correction factor come from my care team.

You don’t need to know the carbs in everything, just the foods you actually want to eat. And be real with yourself. How many M&Ms are really in a serving? Use a scale, and count the nuts. The goal is to be as accurate as you can, so you know, consistently, how many carbs you’re eating.

Eating out? Ask for a nutrition menu! Not every place has one, but it never hurts to ask. If your local spot doesn’t, find a similar meal that does have the numbers, and use it to guesstimate.

What to watch out for on labels

The ones that surprised me with a fast rise

Sugar isn’t the only thing to look for. Starches and syrups made from corn, rice, and potatoes turn into sugar fast, and they show up in foods that don’t taste sweet at all.

On the ingredientsCorn starch, modified food starch, potato and tapioca starchThickeners. They’re in gravies, soups, sauces, and takeout, and they turn into sugar quickly.
On the ingredientsMaltodextrinMade from corn, rice, or potato starch. It can raise blood sugar faster than table sugar,² and it hides in “low sugar” snacks, protein powders, and sweetener packets.
On the ingredientsDextrose, corn syrup, rice syrupAll fast sugars, even when the front of the box doesn’t say “sugar”.
On the front“Sugar free” and “no sugar added”Not the same as carb free. Some sugar alcohols, like maltitol, still raise my blood sugar, and fruit juice concentrate is still sugar.
On the ingredientsWheat vs. whole wheatThis one really got me. “Wheat” or “wheat flour” is usually refined white flour.³ Only “whole wheat” means the whole grain, with more fiber, which can slow the rise.
On the panelServing size vs. the whole bagThe numbers are per serving. Check how many servings are in what you’re actually eating.

My reviewApp · iPhone · Dexcom partner

SNAQ, for checking my carb counts

SNAQ estimates the carbs, protein, and fat in a meal from a photo, then shows how that meal moved my glucose afterward. It’s a Dexcom partner app, so it reads my Dexcom data directly.⁴

Setting it up: Install SNAQ – Diabetes Food Tracker from the App Store.⁵ In its settings, connect your Dexcom account. Then snap a photo of each meal and SNAQ lines it up with your glucose curve.
Good to know: SNAQ sits outside my Nightscout setup. It doesn’t send anything to Nightscout or Zukka, and my followers won’t see it.
What it costs: SNAQ Premium: $60 a year, or $27 every 3 months, or $96 for 3 years on SNAQ’s website. App Store prices vary by plan.⁶ I pay for it. Checked October 2026.
My verdict: Seeing the data is so valuable. When I want to look at my carbs, then reflect on exercise and my blood sugar, this is the best view, because it’s built off my meals.

SNAQ's count for a Chick-fil-A grilled filet with bacon and cheese, waffle fries and honey roasted BBQ sauce: 36 g carbs, 33 g protein, 34 g fat, 580 calories. — One meal in SNAQ: 36 g of carbs, and my glucose stayed in range the whole time.

SNAQ's glucose view for that meal: 100% in range, from 112 before the meal to a peak of 134, a 22 mg/dL rise, 2 h 9 min to peak. — One meal in SNAQ: 36 g of carbs, and my glucose stayed in range the whole time.

2 · Insulin

Timing the bolus

Different devices give insulin in different step sizes. My CeQur patch gives 2 units per click, so a dose is 2, 4, or 6 units. While I was learning, those set amounts helped me stay consistent with meals I eat often, so I could get to know how I respond.

Which insulin I take changes the timing too. Afrezza, the one I inhale, starts in about 12 minutes and is done in 1.5 to 3 hours. Humalog starts in 15 to 30 minutes and lasts 4 to 6 hours.⁷ So how far ahead I bolus, and how long I watch for it still working, depends on which one I’m using.

How each one works → Insulin delivery
Try the timing yourself → Bite 3: Learn now, bolus later

3 · Exercise

When I’m moving

Exercise changes my insulin in two ways, and they work on different clocks. A walk after dinner or a day in the garden changes the math.

Clock 1

The past two days

2 days agolong walk
Yesterdaygarden day
Todayit all adds up

All my exercise over the past two days adds up, not just today’s. The more I’ve done, the more sensitive I am, so each unit works faster and does more.

Clock 2

Right now

Insulin on board+Moving=It acts faster

Moving while I still have insulin on board makes it act faster, because exercise moves it through my bloodstream more quickly.⁸

After a lot of exercise

Pre-bolusing is still the pillar. But after a lot of exercise, the usual head start can be too much, too soon. So I change how I do it.

My usualOne full bolus, 15 minutes aheadOn a normal day, it’s exactly right. After a big day, every unit does more and works faster, so the same bolus can pull me down before the food catches up.

After a lot of exerciseA few quick responsesA small meal? I eat, wait, and respond to what my glucose is doing. A big one with extra carbs? I probably still bolus for the extra, then watch. It really varies.

It’s better to respond quickly a few times than to over-bolus far too soon.

Watching

Set your alerts to match your targets

Responding quickly only works if I know something’s happening. My goals are on the Reports page: 97% of the day between 70 and 180, and over 90% between 70 and 140. So my alerts sit right at those edges. My phone and watch tell me the moment I start to leave my range, while a small fix still works.

All in mg/dL. Solid lines are the urgent alarms; dashed are the early ones. Fast drop and fast rise go off on speed, not a number.

Top of my tight rangeHigh alert at 140The early one. I hear about a rise while it’s still small, so the fix is small too.
Top of my rangeVery high at 180If I get here, the early one didn’t do its job. Time to act.
Bottom of my rangeLow at 75, very low at 70Plus a fast-drop alert, which matters most after exercise, when insulin works faster.

The speed alerts tell me what to do next. A fast drop on a walk is my cue to treat before I get low, not after. A fast rise after a meal can be my cue to go for a walk.

My alarm settings, to copy → Set up your tech

Sources

Bolusing

So many things, all at once

For bolusing, three matter most

Food

Insulin

Exercise