Post Syndicated from Bradley M. Kuhn original http://ebb.org/bkuhn/blog/2025/11/06/juggluco-foss-continuous-glucose-montior-diabetes.html
[ The below is a cross-post of an article that I published on my blog
at Software Freedom Conservancy. ]
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!
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!