DIY Chemistry Points The Way To Open Source Blood Glucose Testing

Every diabetic knows that one of the major burdens of the disease is managing supplies. From insulin to alcohol wipes, diabetes is a resource-intensive disease, and running out of anything has the potential for disaster. This is especially true for glucose test trips, the little electrochemical dongles that plug into a meter and read the amount of glucose in a single drop of blood.

As you might expect, glucose test strips are highly proprietary, tightly regulated, and very expensive. But the chemistry that makes them work is pretty simple, which led [Markus Bindhammer] to these experiments with open source glucose testing. It’s all part of a larger effort at developing an open Arduino glucometer, a project that has been going on since 2016 but stalled in part thanks to supply chain difficulties on the chemistry side, mainly in procuring glucose oxidase, an enzyme that oxidizes glucose. The reaction creates hydrogen peroxide, which can be measured to determine the amount of glucose present.

With glucose oxidase once again readily available — from bakery and wine-making suppliers — [Markus] started playing with the chemistry. The first reaction in the video below demonstrates how iodine and starch can be used as a reagent to detect peroxide. A tiny drop of glucose solution turns the iodine-starch suspension a deep blue color in the presence of glucose oxidase.

While lovely, colorimetric reactions such as these aren’t optimal for analyzing blood, so reaction number two uses electrochemistry to detect glucose. Platinum electrodes are bathed in a solution of glucose oxidase and connected to a multimeter. When glucose is added to the solution, the peroxide produced lowers the resistance across the electrodes. This is essentially what’s going on in commercial glucose test strips, as well as in continuous glucose monitors.

Hats off to [Markus] for working so diligently on this project. We’re keenly interested in this project, and we’ll be following developments closely. Continue reading “DIY Chemistry Points The Way To Open Source Blood Glucose Testing”

Live Glucose Monitoring With The Apple Watch

There has been a rumor that Apple is working on a glucose monitoring solution for the Apple watch. [Harley] decided not to wait and managed to interface an Abbot FreeStyle Libre sensor with the Apple watch. The sensor doesn’t directly read glucose continuously, but it does allow for more frequent reading which can help diabetic patients manage their blood sugar levels. However, as part of the hack, [Harley] effectively converts the meter to a continuous-reading device, another bonus.

The trick is to add a Bluetooth transmitter to the NFC sensor. Using a device called a MiaoMiao, the task seems pretty simple. The MiaoMaio is small, waterproof, and lasts two weeks on a charge, which is longer than the sensor’s life. Honestly, this is the hack since once you have the data flowing over Bluetooth, you can process it in any number of ways including using an app on the Apple watch.

It isn’t perfect. There’s a slight lag with readings due to the way the sensor works. However, you usually don’t care as much about the absolute value of your glucose (unless it is very high or very low). You are usually more interested in the slope of the change. This data is more than good enough for that.

In fact, the most complex part of this seems to be the watch app. It might be less work to feed the data to a machine learning model and let AI guide your insulin injections. Something to think about.

We have a keen interest in glucose monitoring around here and we know why it is so darn hard. Honestly, the idea of pushing glucose meter data to a watch isn’t new, but this is a well-done implementation with a lot of possibilities.

Getting Data Off Proprietary Glucometers Gets A Little Easier

Glucometers (which measure glucose levels in blood) are medical devices familiar to diabetics, and notorious for being proprietary. Gentoo Linux developer [Flameeyes] has some good news about his open source tool to read and export data from a growing variety of glucometers. For [Flameeyes], the process started four years ago when he needed to send his glucometer readings to his doctor and ended up writing his own tool. Previously it was for Linux only, but now has Windows support.

Glucometers use a variety of different data interfaces, and even similar glucometers from the same manufacturer can use different protocols. Getting the data is one thing, but more is needed. [Flameeyes] admits that the tool is still crude in many ways, lacking useful features such as HTML output. Visualization and analysis are missing as well. If you’re interested in seeing if you can help, head over to the GitHub repository for glucomerutils. Also needed are details on protocols used by different devices; [Flameeyes] has only been able to reverse-engineer the protocols of meters he owns.

Speaking of glucometers, there is a project for a Universal Glucometer which aims to be able to use test strips from any manufacturer without needing to purchase a different meter.

Thanks for the tip, [Stuart]!

Hackaday Prize Entry: The Chocometer

Diabetes affects almost 400 million people worldwide, and complications due to diabetes – blindness, cardiovascular disease, and kidney problems – can be reduced by regular monitoring of blood glucose. The usual way of measuring blood glucose is with a pin prick of blood and a small test strip that costs about $0.30. That’s a lot of test strips and blood used by 400 million diabetics every day. Wouldn’t it be better if there was a less invasive way of measuring blood glucose?

[marcelclaro]’s project for The Hackaday Prize aims to do just that. Instead of measuring blood directly, his project will measure blood glucose by shining light through a finger or an earlobe. Using light to detect blood glucose is something that has been studied in the lab, but so far, there aren’t any products on the market that use this technique.

There are two major problems [marcel] needs to overcome to turn this project into reality. The first is simply raw data for calibration. For [marcel], this is easy; he has Type 1 diabetes, and takes four glucose measurements a day. Patient heal thyself, or something.

The second problem is getting a photosensor that’s sensitive enough. By using an InGaAs PIN diode, a current-controlled oscillator, and a digital counter, [marcel] should have a sensor that’s good enough, with electronics that are cheap enough, to create some tech that is truly game changing for a few hundred million people around the world.

The 2015 Hackaday Prize is sponsored by: