Why your care team won't name an app

An app that tells you how much insulin to give is a medical device. In the US, it needs FDA clearance before it can be sold for that, which is why several apps that calculate doses elsewhere switch the feature off for American users. And if a clinic recommends a specific app and it gets a dose wrong, the clinic carries some of that risk.

So most teams stay neutral. They'll still give you your carb ratio, correction factor and target, and many will happily look over an app once you've set it up. Ask them to.

What we used

We're in Canada, where you can't get a pump until you've been on injections for a year. In the first week after diagnosis, we looked for apps to help with the dosing math, and we used Diabetes:M, with the settings from our care team.

The apps

Checked in November 2026. Availability and features change, so confirm in your app store.

Diabetes:M

A full logbook with a Bolus Advisor that works out a meal or correction dose from your settings, and accounts for insulin still active from the last dose. Free, with a paid subscription for extras.

United States
The logbook works, but the developer says the Bolus Advisor isn't available in the US.
Canada
Bolus Advisor available. This is what we used.

BolusCalc

A free, simple calculator from BC Children's Hospital, built for Canadian homes and schools. Meal and correction doses, sliding scales, and adjustments for CGM trend arrows.

United States
Listed on the US App Store, and it handles mg/dL. It isn't FDA-cleared.
Canada
Available on iPhone, iPad and Android.

T1D1

A free dose calculator and log for people on injections, aged 2 and up. It doesn't connect to a CGM, so you type the number in.

United States
FDA-cleared in 2025 as an over-the-counter dose calculator.
Canada
We couldn't confirm it's offered in Canada.

InPen

A reusable smart pen from Medtronic. It records every dose, and its app suggests meal and correction doses. Needs a prescription.

United States
FDA-cleared and available.
Canada
Not available, as far as we can find.

mySugr

A popular, friendly logbook. Its dose calculator is only offered in some countries.

United States
Logbook only. The calculator isn't offered.
Canada
Logbook only. The calculator isn't offered.

On a pump

Every pump and automated system has a dose calculator built in, set up with your care team. You won't need a separate app for the math. See the tools and tech guide.

For looking up carbs

CalorieKing works in both countries, and many dose apps have their own food lists. Avoid diet apps built for weight loss; they're aimed at cutting carbs, not counting them. The food and mealtime guide covers counting.

Before you trust an app with a dose

Set it up carefully

  • Enter the carb ratio, correction factor and target from your care team. Never guess them, and never copy another family's.
  • Check the units. Canada uses mmol/L and the US uses mg/dL. A wrong unit gives a badly wrong dose.
  • Set how long insulin stays active (often 3 to 4 hours), so the app doesn't stack doses.
  • Check every answer against your own math for the first few days.
  • Update the app every time your team changes a setting. Ratios change as children grow.
  • Keep a way to work out a dose without your phone: a printed scale or the steps on paper.
The app does the arithmetic, not the judgment. If an answer looks wrong, or doesn't fit how your child seems, trust that feeling, check again, and call your care team.

Questions for your care team

  1. 1Can you write down our carb ratio, correction factor, target and insulin action time?
  2. 2Would you look over our app's settings once we've entered them?
  3. 3Is there an app your clinic is comfortable with, even if you can't formally recommend one?
  4. 4When should we expect our settings to change?