Managing Diabetes in Software Freedom

by Bradley M. Kühn on November 6, 2025

Our member project representatives and others who collaborate with SFC on projects know that I've been on part-time medical leave this year. As I recently announced publicly on the Fediverse, I was diagnosed in March 2025 with early-stage Type 2 Diabetes. I had no idea that that the diagnosis would become a software freedom and users' rights endeavor.

After the diagnosis, my doctor suggested immediately that I see the diabetes nurse-practitioner specialist in their practice. It took some time get an appointment with him, so I saw him first in mid-April 2025.

I walked into the office, sat down, and within minutes the specialist asked me to “take out your phone and install the Freestyle Libre app from Abbott”. This is the first (but, will probably not be the only) time a medical practitioner asked me to install proprietary software as the first step of treatment.

The specialist told me that in his experience, even early-stage diabetics like me should use a Continuous Glucose Monitor (CGM). CGM's are an amazing (relatively) recent invention that allows diabetics to sample their blood sugar level constantly. As we software developers and engineers know: great things happen when your diagnostic readout is as low latency as possible. CGMs lower the latency of readouts from 3–4 times a day to every five minutes. For example, diabetics can see what foods are most likely to cause blood sugar spikes for them personally. CGMs put patients on a path to manage this chronic condition well.

But, the devices themselves, and the (default) apps that control them are hopelessly proprietary. Fortunately, this was (obviously) not my first time explaining FOSS from first principles. So, I read through the license and terms and conditions of the ironically named “Freestyle Libre” app, and pointed out to the specialist how patient-unfriendly the terms were. For example, Abbott (the manufacturer of my CGM) reserves the right to collect your data (anonymously of course, to “improve the product”). They also require patients to agree that if they take any action to reverse engineer, modify, or otherwise do the normal things our community does with software, the patient must agree that such actions “constitute immediate, irreparable harm to Abbott, its affiliates, and/or its licensors”. I briefly explained to the specialist that I could not possibly agree. I began in real-time (still sitting with the specialist) a search for a FOSS solution.

As I was searching, the specialist said: “Oh, I don't use any of it myself, but I think I've heard of this ‘open source’ thing — there is a program called xDrip+ that is for insulin-dependent diabetics that I've heard of and some patients report it is quite good”.

While I'm (luckily) very far from insulin-dependency, I eventually found the FOSS Android app called Juggluco (a portmanteau for “Juggle glucose”). I asked the specialist to give me the prescription and I'd try Juggluco to see if it would work.

CGM's are very small and their firmware is (by obvious necessity) quite simple. As such, their interfaces are standard. CGM's are activated with Near Field Communication (NFC) — available on even quite old Android devices. The Android device sends a simple integer identifier via NFC that activates the CGM. Once activated — and through the 15-day life of the device — the device responds via Bluetooth with the patient's current glucose reading to any device presenting that integer.

Fortunately, I quickly discovered that the FOSS community was already “on this”. The NFC activation worked just fine, even on the recently updated “Freestyle Libre 3+”. After the sixty minute calibration period, I had a continuous readout in Juggluco.

CGM's lower latency feedback enables diabetics to have more control of their illness management. one example among many: the patient can see (in real time) what foods most often cause blood sugar spikes for them personally. Diabetes hits everyone differently; data allows everyone to manage their own chronic condition better.

My personal story with Juggluco will continue — as I hope (although not until after FOSDEM 2026 😆) to become an upstream contributor to Juggluco. Most importantly, I hope to help the app appear in F-Droid. (I must currently side-load or use Aurora Store to make it work on LineageOS.)

Fitting with the history that many projects that interact with proprietary technology must so often live through, Juggluco has faced surreptitious removal from Google's Play Store. Abbott even accused Juggluco of using their proprietary libraries and encryption methods, but the so-called “encryption method” is literally sending an single integer as part of NFC activation.

While Abbott backed off, this is another example of why the movement of patients taking control of the technology remains essential. FOSS fits perfectly with this goal. Software freedom gives control of technology to those who actually rely on it — rather than for-profit medical equipment manufacturers.

When I returned to my specialist for a follow-up, we reviewed the data and graphs that I produced with Juggluco. I, of course, have never installed, used, or even agreed to Abbott's licenses and terms, so I have never seen what the Abbott app does. I was thus surprised when I showed my specialist Juggluco's summary graphs. He excitedly told me “this is much better reporting than the Abbott app gives you!”. We all know that sometimes proprietary software has better and more features than the FOSS equivalent, so it's a particularly great success when our community efforts outdoes a wealthy 200 billion-dollar megacorp on software features!

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Please do watch SFC's site in 2026 for more posts about my ongoing work with Juggluco, and please give generously as an SFC Sustainer to help this and our other work continue in 2026!

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