01
Insulin dose calculator
Real-time dose calculation based on current glucose and carb intake, paired with a predictive glucose graph showing the expected post-meal trajectory.
ColibriGC
iOS
Healthcare
Product Design
User Research
Deprecated · 2018
ColibriGC (Colibri Glucose Control) is an iOS app that helps people with diabetes track glucose readings, carbohydrate intake, and insulin consumption — reducing cognitive load with a built-in dose calculator and three-month trend analysis. Shipped to the App Store in 2018 after nine months of research, design, and prototyping.
4.5★
App Store rating
75%
Weekly engagement
400+
Downloads · 6 mo
Credits
Team and role.
Product Designer
User research with insulin-dependent users, problem framing around dose-math accuracy and on-the-go usability, information architecture for the diary + calculator + statistics surfaces, UX/UI for iOS, interactive prototyping with live calculations and a predictive glucose graph, moderated usability testing with ten participants, healthcare-grade accessibility.
Development handoff
Implementation by a partner iOS team. Handoff package included full specs, the interactive prototype, the personalised insulin-to-carb-ratio model, and three rounds of QA against the usability-test findings before App Store release.
The product
Diabetes management, simplified.
ColibriGC empowers insulin-dependent users to manage diabetes effortlessly. It logs glucose readings, carbohydrate intake, and insulin consumption; calculates dosage in real time; and surfaces long-term trends — turning a daily mental-arithmetic burden into a glanceable, actionable workflow.
The challenge
Critical math, complex interfaces.
Managing diabetes means balancing glucose, carbs, and insulin every day — but the existing tools made dose calculation slow, error-prone, and impersonal. Dashboards were dense, personalization was thin, and trend analysis was missing. Errors here aren't just inconvenient; they're medical.
“How might we simplify insulin dosage calculation while giving users actionable insights into how their body responds over time?”
Features
Four things the product does.
02
Diary
A single screen to log glucose readings, carbs, and insulin — with immediate, actionable insight on each entry instead of raw numbers waiting to be analyzed.
03
Statistics & trends
Three-month visualizations with averages designed to be screenshot-ready for medical appointments — the conversation with a doctor starts with data, not memory.
04
Personalization
Insulin-to-carb ratios are unique to each person. The settings let users tune the calculator to their own body, instead of forcing a generic profile.
The four features at a glance: calculator, diary, statistics, and personalization on a single canvas.
Process · Research
Three pain points, one product brief.
I started with moderated interviews of insulin-dependent users [NEEDS: sample size + demographic mix] and a competitive audit of the diabetes-management apps already on the store. The same three pain points surfaced across every conversation: dose-calculation accuracy, personalization (the existing tools assumed everyone had the same insulin-to-carb ratio), and on-the-go usability (the apps were designed for a calm desk, not a restaurant table mid-meal).
Defining decision
Errors here aren't inconvenient — they're medical. Dose math had to become the design's job, not the user's burden. Every subsequent decision (the calculator's live readout, the predictive glucose graph, the personalised insulin-to-carb ratios in settings) worked back from this single framing.
Process · Validation
Tested with ten participants before launch.
From low-fi wireframes I built an interactive prototype with live calculations and a predictive glucose graph, then ran moderated usability testing with ten participants. Task completion, error rates, and satisfaction scores drove a final round of iteration before launch — and became the headline pre-launch metrics on the outcomes panel below.
From low-fi wireframes to the interactive prototype that drove usability testing — and into the handoff package the iOS partner team built against.
90%
Task completion · without errors
4.7/5
Satisfaction score
10
Test participants
“Finally a diabetes app that does the math for me instead of making me redo it on my phone calculator at the dinner table.”
Marcus · Type 1
Outcomes
What shipped, what stuck.
4.5★
Average App Store rating across the product's first six months —
a consumer signal that the dose-math automation and on-the-go
usability decisions actually landed for the people they were
designed for.
400+
Downloads · first 6 mo
75%
Weekly engagement
60%
3-month retention
Stack
Tools and methods.
iOS
Xcode
User research
Prototyping
Usability testing
Healthcare UX
“ColibriGC was the project that taught me design has stakes. When someone is dosing insulin off your interface, clarity isn't a preference — it's the deliverable. The lessons from this work shape how I approach every product since.”
ColibriGC is no longer maintained or available on the App Store. The case study is preserved here as a record of the work.