By IDS intern Amber Jackson, RN, DCES
Designed by a student with T1D, T1D1 is a personal insulin-calculation app designed to help users manage daily diabetes care by calculating and tracking insulin doses.
Recently FDA-cleared, it stands out as the only over-the-counter insulin calculator currently cleared in the U.S.
My Experience
To see how it stacks up, I tested the T1D1 app on iOS for two weeks. Its key features include a clean and simple interface, personalized insulin settings, a food library, a dosage calculator, and a logbook for quicker tracking. The app prioritizes simplicity, which is ideal for users who don’t want complex dashboards or overly technical features.
Key Evaluation Areas:
✔ Ease of Use / User Interface
The interface is simple, clean, and efficient. Navigation is intuitive, and every feature is easy to locate. It’s designed for users who prefer straightforward tools rather than advanced customization. Those who need deeper personalization or automation may find the app too minimalistic.
✔ Features & Functionality
T1D1 calculates bolus insulin using a combination of user-entered settings, including:
- Basal insulin
- Target blood glucose (70–100 mg/dL)
- Correction factor (1–400 mg/dL)
- Carb ratio (1–150 g/unit)
- Current blood glucose
- Total carbs
The app allows multiple calculator profiles for different times of day, though it does not switch them automatically.
Additional features include:
- Correction-only calculations when carbs = 0
- Optional negative correction to prevent hypoglycemia
- A detailed formula breakdown for each calculation
- A notes section
- A bolus history log
- A food library (though items cannot be selected directly to auto-populate the calculator)
- Allows you to log basal insulin
Advanced settings include mg/dL vs mmol/L units, rounding preferences (none, half-unit, whole-unit), and the option to display the calculation formula. It also allows for renaming insulin profiles for specific adjustments such as exercise, illness, or other temporary factors that influence insulin needs.
Notably, the app does not integrate with CGMs, so blood glucose must be entered manually. The advanced settings must be modified each time through the main settings page and cannot be adjusted quickly when calculating the dosage.
✔ Performance
During testing, the app performed smoothly with no crashes or bugs. Loads quickly—there is a brief loading screen (featuring a playful Pac-Man animation), but it lasts less than a second.
✔ Design & UX
The design is minimal and friendly. Users can upload a profile photo, and the interface avoids clutter, making it approachable for beginners and non-tech-savvy users.
✔ Pricing / Value
The app is completely free, FDA-cleared, and rated for ages 12+. It is currently available only in English. Developed by T1D1.
Pros & Cons
Pros
- Clean, simple interface
- Accurate insulin calculations
- Allows for advanced insulin profile settings for illness, exercise, etc.
- Helpful logbook and notes
- Free and FDA-cleared
Cons
- No CGM integration
- Food library doesn’t link directly to calculations
- Does not auto-switch calculator profiles
- Inconvenient for quick or advanced setting changes
- English-only
Recommendation
T1D1 is a strong choice for individuals seeking a simple, reliable insulin-calculation tool without added complexity. It’s best suited for insulin-pen users or anyone who prefers manual input and straightforward features.
It is especially preferred for users with a consistent daily routine who do not need quick or advanced setting changes.
Power users looking for automation, CGM syncing, or dynamic adjustments may find it limited, but its accuracy and FDA clearance make it a trustworthy everyday companion.
