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Haley Maddox
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Interactive guide · Type 1

Learn now, bolus later

It's never too early to learn bolus strategies.

An interactive guide to bolus timing. Pick a food and an insulin, then slide the bolus to see what happens when you take it early, right on time, or late.

Then go further below: five foods, two insulins, bigger meals, and split doses. This is the kind of visualization I was trying to understand when thinking through bolus strategies. These tools are not to be used for dosing or medical decisions.

Coll. Haley Maddox · Oct 2026

Humalog4 units
Afrezza4 units
Same 40 g, two very different curves.
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

Try it

Insulin works best when it lines up with the food. This builds on the bolusing guide and the glycemic index guide. Every dose here uses a 1 unit to 10 g carb ratio: 4 units for 40 g, 8 units for 80 g. Only the insulin and the timing change.

Mode

Every food is 40 g of carbs with 4 units of insulin. Advanced adds 80 g meals and split doses.

Food

Insulin

Glucose sketch for the chosen food, insulin, and timing
At the first bite–
Peak–
Goes low–
Goes high–

A teaching sketch of timing over 8 hours, not your body and not a dosing tool.
The math is round on purpose: 1 unit covers 10 g of carbs, and Afrezza and Humalog count the same. That keeps the numbers easy so the timing stands out. Your own doses come from your care team, not from this page.
Notice

Patterns

The flattest glucose line comes when the two shaded humps under the chart line up: carbs arriving, and insulin at work. Try these.

Pizza dose-splitting study: Jones et al., 2005 (pump users, Humalog). The Afrezza and Humalog split on this page is a sketch, not a tested plan.

Compare

The insulins

Humalog Insulin lispro, injected under the skin.
To start
15–30 min
Peak
1–2 h
Lasts
4–6 h
When
0 to 15 minutes before a meal, or soon after when needed
Afrezza Inhaled insulin powder, one breath per cartridge.
To start
About 12 min
Peak
35–55 min
Lasts
1.5–3 h
When
At the beginning of the meal
Me
I take it when my glucose starts to rise
Doses
4-, 8-, and 12-unit cartridges

Afrezza's label carries a boxed warning: it can cause sudden bronchospasm, so it isn't for people with chronic lung disease such as asthma or COPD, and lung function is checked before starting. It's approved for ages 6 and up.

Sources: timing for both from the ADCES insulin types chart; Humalog meal timing from its product information; Afrezza meal timing, cartridges, and warning from its prescribing information (FDA, 2026).

Test

Test it

The chart is a sketch for seeing timing. The idea behind it is simple: glucose goes up as carbs arrive and down as insulin works. When the two line up, glucose stays steady. When one gets ahead, it moves.

What the sketch assumesRound numbers: 1 unit for every 10 g of carbs, and the same for Afrezza and Humalog. Each food's speed comes from its glycemic index, and fat adds a late rise. Each insulin's timing comes from its label. Everything else that changes a real day is left out.

How to think about testing your own timing

  • Watch the shape, not one number. On your CGM, notice when glucose starts to rise, when it peaks, and when it settles after a meal.
  • Repeat the same meal. One day can mislead. The same food on a few different days shows your pattern.
  • Change one thing at a time. Timing, food, or insulin. If you change two, you can't tell which one mattered.
  • Look later, too. Fatty meals can rise hours after eating, long after a fast insulin is done.
  • Bring it to your care team. Your CGM history is what they need to help you adjust timing or doses safely.

Sources: food speeds and carb amounts from the Harvard Health table; fat and insulin from Bell et al., 2015 (summary); insulin timing from the labels listed below.

Review

Sources

  • Humalog 100 units/ml solution for injection: summary of product characteristics. medicines.org.uk
  • Afrezza (insulin human) inhalation powder: prescribing information. MannKind, 2026. accessdata.fda.gov
  • Association of Diabetes Care & Education Specialists (ADCES), danatech. Insulin types. adces.org
  • Harvard Health Publishing. Glycemic index and glycemic load for 100+ foods. health.harvard.edu
  • Centers for Disease Control and Prevention. Treatment of low blood sugar (hypoglycemia). cdc.gov
  • Wolpert HA, Atakov-Castillo A, Smith SA, Steil GM. Dietary fat acutely increases glucose concentrations and insulin requirements in patients with type 1 diabetes. Diabetes Care. 2013;36(4):810–816. Conference report: MDedge
  • Bell KJ, Smart CE, Steil GM, Brand-Miller JC, King B, Wolpert HA. Impact of fat, protein, and glycemic index on postprandial glucose control in type 1 diabetes. Diabetes Care. 2015;38(6):1008–1015. Summary: HealthDay
  • Jones SM, Quarry JL, Caldwell-McMillan M, Mauger DT, Gabbay RA. Optimal insulin pump dosing and postprandial glycemia following a pizza meal using the continuous glucose monitoring system. Diabetes Technol Ther. 2005;7(2):233–240. Penn State abstract