# Continuous Glucose Monitoring

DevFeed: [Continuous Glucose Monitoring](<https://devfeed.tech/articles/continuous-glucose-monitoring-36614.md>)

Original publisher: [Read original article](<http://www.imperialviolet.org/2025/06/29/cgm.html>)

Author: Adam Langley

Published: 2025-06-29T00:00:00Z

Content type: opinion

Language: en

Sources: [ImperialViolet](<https://devfeed.tech/sources/imperialviolet.md>)

Topics: [data](<https://devfeed.tech/topics/data.md>), [Monitoring](<https://devfeed.tech/topics/monitoring.md>), [App](<https://devfeed.tech/topics/app.md>), [Android](<https://devfeed.tech/topics/android.md>), [iphone](<https://devfeed.tech/topics/iphone.md>)

Tags: [android](<https://devfeed.tech/tags/android.md>), [app](<https://devfeed.tech/tags/app.md>), [data](<https://devfeed.tech/tags/data.md>), [iphone](<https://devfeed.tech/tags/iphone.md>), [monitoring](<https://devfeed.tech/tags/monitoring.md>), [technology](<https://devfeed.tech/tags/technology.md>)

## AI overview

A personal review of over-the-counter continuous glucose monitoring. The author describes the sensor, its reading and transmission intervals, phone requirements, app experience, and physical application, based mainly on testing with an iPhone.

## Source excerpt

Continuous glucose monitoring has been a thing for a while. It's a probe that sits just inside your body and measures blood glucose levels frequently. Obviously this is most useful for type 1 diabetics, who need to regulate their blood glucose manually. (At this point, I would be amiss not to give a nod to the book Systems Medicine, which I think most readers would find fascinating. I can't judge whether it's correct or not, but it is a delightful exploration of a bunch of maladies from the perspective of differential equations.) But CGMs have been both expensive and prescription-only. And I am not a diabetic, type 1 or otherwise. But technology and, more importantly, regulation have apparently marched on, and even in America I can now buy a CGM for $50 that lasts for two weeks, over the counter. So CGM technology is now available to the mildly curious, like me. The device itself looks like a thick guitar pick, and it comes encased inside a much larger lump of plastic that has a pretty serious-looking spring inside. It takes readings every 5 minutes but only transmits every 15 minutes. You need a phone to receive the data and, if the phone is not nearby, it will buffer some number of samples and catch up when it can. The instructions say to keep the phone nearby at all times, so I didn't test how much it will buffer beyond an hour or so. I've got both an Android and an iPhone, but for this the iPhone was a more convenient device. So everything following probably applies to both ecosystems, but I've only tested it in one. The app is well made, although you can feel the lawyers & regulators hovering over every part of it. It gives you instructions about how to "install" the sensor, which you do by holding the big lump of plastic with the spring over a suitable spot on your body and then pressing the button. It's not a large needle, but it's not trivial either. There is a soupçon of cyberpunk about applying it to yourself in the bathroom but, honestly, my first thought