No More Needles: Best Non-Invasive Glucose Monitors

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According to a 2017 report, more than 100 million Americans suffer from some form of diabetes or pre-diabetes. This means that there is a huge proportion of the population whose lives depend on a strict regimen of a low glycemic index diet and regular monitoring of glucose levels.

Getting diagnosed with diabetes is a life-changing moment for many people. One of the most drastic changes that a diabetic must go through is the need to monitor blood glucose levels regularly. This can be a painful and tedious commitment. Can non-invasive glucose monitors provide relief for diabetics? Are they just as reliable and accurate? What are the best ones available today?

What are the benefits of non-invasive glucose monitors?

In either Type 1 or Type 2 diabetes, the pancreas loses the ability to produce insulin, which is a hormone that regulates the body’s glucose levels and produces energy. This puts them at risk of either hyperglycemia (too high glucose levels) or hypoglycemia (too low glucose levels). Either outcome is undesired, as they can lead to eye problems, blood circulation problems, and heart and kidney issues.

The first line of defense against the consequences of diabetes is regular blood glucose monitoring. The traditional and most widely practiced way to do this is to draw a small amount of blood, typically by pricking a finger using a lancet. Because of the pain and discomfort of the process, regular blood sugar monitoring becomes a huge chore – one that many people fail to do regularly.

Non-invasive and needle-free methods to test for blood glucose are now being developed to ease the burden for diabetics. They may also end up cheaper in the long run, as diabetics can do away with having to buy disposable lancets and test strips. The goal of non-invasive glucose monitoring technology is to make the process as easy and painless as possible so that diabetics can do it as prescribed, even up to 5 times a day.

Modern non-invasive glucose monitors interface with smartphones, making it so much easier to document your blood sugar levels through the weeks or even within the day. With the possibility of automated measurements, these advanced blood glucose monitors could provide insight about when or why your blood sugar drops.

How do they work?

The scientific community has been hard at work trying to come up with ways to detect blood sugar levels without having to draw blood since the 1970s. Today, there are several promising methods available, each with its benefits and limitations. Some of the most commonly used methods include:

  • Measurement on infrared radiation emitted by the body
  • Application of radio waves to the fingertips
  • Using a beam near-infrared energy that can penetrate the skin
  • Using ultrasound waves to penetrate the skin
  • Measurement of the viscosity of fluids underneath the skin

Hundreds of millions of dollars’ worth of investment have been poured into this research, yet there has not yet been any technology that can be declared as the best method for non-invasive glucose monitoring. Although further research is still needed to improve the accuracy and reliability of these methods, that has not stopped manufacturers from developing and marketing consumer-ready glucose monitors.

The best non-invasive glucose monitors in the market

If you’re considering buying a non-invasive glucose monitor, then there isn’t exactly a shortage of choices in the market today. However, this is your health we are talking about, so it’s worth the time to stop and choose carefully.

The simplest way to pare down the selection is to only choose between the devices that have received FDA approval. The FDA started reviewing and approving these devices back in 2017, and the list has grown by quite a lot since then. This is great news, of course. As competition in this field thrives, the products will tend to get better, smarter, and easier to use – as you shall see in this list.

1. FreeStyle Libre Flash


The FreeStyle Libre holds the distinction of being the very first non-invasive glucose monitoring device that was approved by the FAA. Touted as the future of diabetes care, the FreeStyle Libre sensor works by first installing a sensor on the back of your upper arm. This may seem to be counter-intuitive with the ‘non-invasive’ tag, but you only have to do this once every 2 weeks or so. Just remember to be careful with it, as it can rip off with a sudden or strong force.

The sensor looks like a tiny white disk that attaches to your arm with a small needle. Each sensor packs comes with detailed instructions on how it is applied. It’s a fairly simple process that you can do yourself, and it takes just a minute or two.

Since it’s only installed beneath your layer of skin, the sensor measures the amount of sugar in the interstitial fluids, and not in your blood. This isn’t really a problem as your body eventually reaches homeostasis anyways, but there might be a delay of about 15 minutes before the sensor can measure your actual blood sugar.

Once the sensor is in place, getting your blood sugar level is as easy as scanning the sensor using the included reader or even with just a smartphone app. The sensor can store data for up to 8 hours, and the reader can illustrate the time-series data with a graph. This is very handy if you’re taking insulin or if you’re about to do some physically demanding activity.

Depending on your level of activity, each sensor will last between 10 to 14 days. They cost between $30 to $40 apiece. The reader costs about $70, but it’s just a one-time purchase.

The Freestyle Libre is cheap and easy to use. However, it does not completely do away with consumables, as the sensors have very short lives. It’s also not completely non-invasive, as you still need the sensor attached to your arm using a needle. This device is great for when you have to go on short periods where you can’t test your blood sugar the old-fashioned way, such as on vacations or out-of-town trips. However, we don’t see it being a long-term, sustainable alternative.

2. GlucoWatch G2 Biographer

The GlucoWatch G2 Biographer, developed by California-based Cygnus Inc., is another device that has received FDA approval. It’s essentially a wristwatch that provides six measurements per hour while you are wearing it. The device also relies on a single-use disposable component, the AutoSensor, which is an adhesive patch that attaches to the back of the Biographer and comes in contact with the skin. Each AutoSensor lasts for 13 hours, yield a total of 78 readings. A 2-hour warm-up period will be needed for every AutoSensor installation before it can start any measurements.

The GlucoWatch pulls interstitial fluids from the skin using a series of small electric currents. The device takes a few minutes to process the data from the samples, so each reading is about 15 minutes delayed from the actual blood sugar level. The device can be programmed with alarms for high and low glucose levels, while a separate, non-removable alarm will be activated if a rapid drop in glucose is detected.

However, don’t throw out your old blood glucose meter and lancets just yet. The FDA has made it quite clear in their approval document that the GlucoWatch is not meant to replace a regular blood glucose meter. In fact, part of the warming up process for each AutoSensor requires that you calibrate the GlucoWatch readings with the one you took using your usual blood glucose test kit. According to the FDA recommendations, the GlucoWatch G2 Biographer is meant to supplement, and not replace, the old-fashioned way of measuring your blood sugar.

This does seem disappointing, especially considering that the GlucoWatch G2 is one of the most convenient non-invasive blood glucose monitors out there. It’s great for situations where you really need to look at the trends of your blood sugar over time, but the FDA hasn’t quite vouched for its accuracy.

3. EverSense CGM


One of the more recently approved devices, the EverSense CGM attempts to fill a niche for non-invasive glucose monitoring devices that offer Continuous Glucose Monitoring (CGM) features. This was the first FDA-approved CGM system.

The EverSense CGM relies on a small implantable sensor that is placed under your skin. The sensor looks like a very small capsule and requires a doctor to do a minor operation (with small incisions) to implant it. Again, this may be troubling for some people, especially since it involves a doctor actually having to cut you open. Honestly, it sounds worse than it actually is. The good news is that each sensor lasts up to 90 days – a huge upgrade to the other embedded sensors for glucose monitoring.

The sensor contains a polymer that fluoresces or lights up according to the levels of glucose that it detects. A transmitter is then worn over this sensor, above the skin, which provides power and allows for data transmission every 5 minutes. The CGM curves can be monitored and reviewed on your smartphone. The transmitter also has built-in alarms for low and high glucose levels.

There are a couple of things that the EverSense has going for it. The fact that the sensor is embedded inside the skin means that there’s no danger of it accidentally getting ripped off. The extended lifetime for each sensor is really great, as it means that you won’t need to replace it every week. It also claims to be the most accurate sensor in the CGM market – a claim that has been reinforced by the experience of many users.

What could be a potential deal-breaker is the need to have to pay your doctor a visit every time you need your sensor changed. With a 3-month period for each sensor, that’s going to translate to four additional visits per year, and that’s if everything goes smoothly. If the installation site gets infected, you’ll likely have to go back again.

4. GlucoTrack


GlucoTrack is still undergoing the process for FDA approval but has the potential to be one of the most non-invasive ways to measure blood sugar. Developed by Israel-based Integrity Applications, GlucoTrack only requires that the sensor be clipped to your ear to make measurements. The technology relies on a combination of ultrasonic, electromagnetic, and thermal waves. The combination of the data collected goes through a unique proprietary algorithm to calculate a weighted average for the user’s blood sugar level.

While its FDA approval is still pending, it has also ready been commercialized in Europe where it has been approved for use. Through a series of official clinical trials held in the Soroka University Medical School, more than 97% of the readings made by GlucoTrack fall within clinically acceptable zones when compared to more traditional blood sugar measurement methods. Thousands of data points from hundreds of diabetics were used to cement this claim and for GlucoTrack to receive the CE Mark.

Although there are no strips that need to be replaced every use, Integrity Applications recommends that you replace the ear clip of the GlucoTrack every six months to ensure accurate measurements. You’ll still need to do a calibration for every ear clip replacement by comparing the readings to those from the “pin-prick” method.

While FDA review is ongoing, the creators of GlucoTrack continue to work to improve its calibration procedure and data processing algorithms. There is a lot of potential for this technology, and there are certainly thousands of diabetics in the US looking forward to its FDA approval.

5. EasyGlucose

We’re cheating a bit here, as EasyGlucose isn’t an FDA-approved device. In fact, it isn’t even a device. EasyGlucose is a cloud-powered software platform that uses machine learning techniques to analyze tiny details in the eye’s iris and use this data to infer the person’s blood sugar level. It sounds too amazing to be true, but EasyGlucose just won this year’s Imagine Cup, an annual student startup competition by Microsoft. Clearly there’s something in this technology that is worth exploring.

Even a smartphone can be used to take photos that the software can analyze, although you’ll need to attach a good macro lens to get the appropriate level of detail. Preliminary tests have shown that the blood sugar levels deduced by EasyGlucose come within 7% of the results of traditional blood sugar meters. This is a better mark than most non-invasive glucose monitoring devices have managed to hit. The creator of the software, Bryan Chiang, seems determined to close this gap.

EasyGlucose has the potential to be one of the cheapest non-invasive glucose monitoring technologies. Chiang is estimating a price of $10 for the lens adapter and a $20 per month subscription to support software development. The technology has been patented, but it has not yet gone through FDA approval. This is exciting news for many diabetics the world over – now there really is an app for everything.

Final thoughts

Although there hasn’t been a definitive technology that can be considered as the standard for non-invasive glucose monitoring, the good news is that the technology seems to have evolved really quickly in the past few years. From implants that last two weeks at most, we now have implants that last several months. We might even have truly a non-invasive glucose monitoring method available in the market soon – one that does not need to go under your skin and has minimal consumables.

For diabetics, these new technologies represent the possibility of an improvement in the quality of their lives. No longer do they have to go through the pain of pricking their fingers to test their blood sugar. Soon enough, all they might need to do is take a picture of their eyes and let some powerful computer do all the work.