DOS BTS
DOS On Sugar, Built To See: an iOS glucose app for Freestyle Libre sensors, with meal and insulin logging and an amber CGA screen. In TestFlight since March 2026.
Overview
Daily Digest
Log Meal
Settings
State of the build
The problem
Glucose readings, meals and insulin usually sit in separate apps, so the glucose chart never shows why a curve went up. Logging a meal by hand takes long enough that it often doesn't happen.
The solution
DOS BTS started on 2026-02-28 as a fork of GlucoseDirect, which already reads Libre sensors. I added meal and insulin logging on top, put both on the glucose chart, and built a Daily Digest that sums up each day.
Data is stored on the device. The AI features are opt-in behind a consent toggle. When they are on, meal photos and text go to the Anthropic API for food analysis, and the daily insight sends glucose, meals, insulin, exercise and journal text.
What it does
Sensor connection
Libre 1 through a Bubble, Libre 2 over NFC and Bluetooth, Libre 3 through the LibreLinkUp cloud follower.
Glucose chart
Insulin on board, a meal-impact overlay and an event-marker lane on one chart.
Food logging
Photo, text, barcode, voice or Siri, with favourites and recents for repeat meals.
Hypo help
A predictive low alarm with a projection line, and guided treatment by the Rule of 15.
Daily Digest
Time in range, lows, highs, carbs and insulin for each day, plus an opt-in AI insight.
Ratio Lab
Estimates insulin-to-carb ratio and correction factor from the data I logged.
Clinic report
A clinic-visit summary exported as PDF and CSV.
Amber CGA look
The whole app in DOS amber, a phosphor home-screen widget and an optional CRT scanline.
Architecture
A SwiftUI app for iOS 26 and later. GRDB over SQLite keeps readings, meals and insulin on the device. HealthKit handles Apple Health import and export, WidgetKit the widget, App Intents the Siri logging, and the Speech framework the voice input. Claude Haiku, through the Anthropic API, analyses food and writes the daily insight, only when AI features are switched on.
Tech stack
Dev Journal
Build log
The AI staging plate can swap an item for one from history or add one by barcode. Meals can be counted, and hypo treatment has its own picker.
Experimental Chart Lab tabs (Build 137) and a refreshed app icon (Build 138).
Live speech-to-text in Log Meal, and journal notes with tags (Builds 134-135).
ICR and ISF estimates from logged data, a missed-bolus nudge, a food-impact ranking, clinic-visit export as PDF and CSV, and one consolidated set of design tokens.
A new entry model, a glucose bar that stays on screen, tight-control streaks (80-120 mg/dL) and an in-app What's New.
Day and night alarm profiles, insulin and meal logging through Siri, and a digest reminder.
An Overview that fits one screen, tab-aware chart zoom, a Statistics tab and an About page in Settings.
An insulin-on-board model (Build 54), a meal-impact overlay with a glycemic score, an event-marker lane on the chart, the Daily Digest tab with an AI insight, and the phosphor widget.
Guided hypo treatment by the Rule of 15, a predictive low alarm with a projection line, and the first XCTest suite.
A Libre-inspired layout and a sensor-disc app icon.
Favourites and recents, AI results you can edit and that learn from corrections, natural-language food parsing, and barcode scan through Open Food Facts.
The amber CGA design on every view, the first TestFlight deploy, a food logging MVP, HealthKit import and export, and AI food photo analysis.
Forked GlucoseDirect and renamed it DOSBTS.
Part of Timeline OS
DOS BTS is a "mod" in the Timeline OS ecosystem focused on health data. Your glucose readings, meals, and health insights flow into your personal timeline, connecting with sleep, activity, and stress patterns.