As far as our body's energy needs are concerned, blood sugar is as sweet as it sounds. While people with diabetes need to monitor its levels to ensure their body has the appropriate amount to stay safe, blood sugar (or blood glucose) is everybody's primary form of energy. How well the body uses blood sugar is also a measure of metabolic health -- a term the medical community is still working out that describes how the body uses energy, and how at-risk someone may be for health problems like heart disease.

But accurately tracking blood sugar, or even putting a firm finger on what it means to be "metabolically healthy," is tricky. Consumer wearables like smartwatches and smart rings can't measure blood glucose, despite the existence of some counterfeit devices on the market that haven't been FDA cleared. 

The world of blood sugar has been the domain of diabetes tech companies, which already have sensors and technology -- continuous glucose monitors -- many people with diabetes use every day. And the companies leading diabetes tech have also been laying down the framework to make metabolic health more mainstream. 

In addition to people with diabetes, continuous glucose monitors have been used for "biohacking" glucose levels by people who want to know how their body responds to food or what impacts their glucose levels. Companies such as Nutrisense use CGMs that require a prescription, but take care of it through their websites.

This month, the US Food and Drug Administration cleared two new CGMs from Abbott for use without prescription: One for people with Type 2 diabetes who don't require insulin (the Libre Rio), and the other a consumer-friendly patch for the general public (the Lingo, which made its debut at CES 2022). Both of Abbott's over-the-counter CGMS are based on its popular FreeStyle Libre sensor technology. 

Rolling out in late August is Dexom's Stelo, a prescription-free CGM designed for people with diabetes who don't need insulin. It was cleared by the FDA earlier this year, making it the first over-the-counter CGM.

Here's what we know about the new over-the-counter CGMs, as well as insight from a company working on a new, non-invasive way to measure blood sugar.

Read more: The FDA Wants to Remind You That Your Smartwatch Can't Measure Blood Sugar Yet 

Over-the-counter CGMs are rolling out this summer. Who actually needs one?

Dexcom said the Stelo will be available in late August. It's designed for people with Type 2 diabetes who don't need to take insulin but it's been cleared by the FDA for any adult who wants to "better understand how diet and exercise may impact blood sugar levels." 

Like other wearable sensors used by people with diabetes, Stelo attaches to your upper arm. A tiny sensor that goes slightly below your skin then reads blood glucose information and sends it to a paired app, allowing you to track your blood sugar information throughout the day and make note of any trends. 

Abbott's consumer biosensor, the Lingo, will also be available this summer, the company said. It didn't provide a timeline for when the Libre Rio, which is meant for people with Type 2 diabetes, will be available.

However, the question of "who actually needs these?" remains. As Dr.Robert H. Shmerling wrote in an article for Harvard Health Publishing, CGMs can cost several thousand dollars a year, and companies marketing their use for the general public stand to make a big profit in an area of health that, as of now, does not have the research supporting it outside diabetes management. In its press release, Abbott pointed to research finding that just 12% of American adults are considered "metabolically healthy," but glucose measurements are just one of a few factors used to qualify metabolic health. 

On the other hand, 1 in 3 Americans have prediabetes -- a step before Type 2 diabetes which can be reversible. Providing actionable information on higher-than-average blood sugar trends could provide many people with the information needed to make choices for their health -- if they can afford it, that is. Neither Dexcom nor Abbott have provided exact prices for their consumer CGMs at this time, but costs for CGMs for people with diabetes who do not have health insurance remains a barrier to health care access. 

Because consumer CGMs don't require a prescription and many cases likely wouldn't be considered medically necessary, someone who may have a higher risk of developing Type 2 diabetes would still likely pay top dollar for an over-the-counter CGM. The high cost of biosensors is one reason there's interest in non-invasive, even more consumer-friendly measures of tracking blood sugar.

Read more: An AI-Built 'Digital Twin' Could Improve Your Health, This Startup Says 

Non-invasive blood sugar monitoring makes an appearance at the American Diabetes Association conference

There's no way to accurately measure blood sugar levels without getting at least a little bit under someone's skin. Even CGMs require a tiny sensor on the wearable patch, even though it's arguably less invasive than a finger prick. 

One company, Know Labs, is working to change that. The company was at the American Diabetes Association Scientific Sessions in Orlando over the weekend and presented promising results on the ability of its wearable device, the KnowU, to get stable readings of blood sugar without penetrating the skin. The company is still a ways out from having a device ready for the market and it's still collecting data to send to the FDA -- the prototype is still bulkier than a CGM, potentially making it a harder sell even if it's less invasive. But the company is expanding on the idea and use of photonics and sensors already integrated (for different purposes) into smartwatches and used to measure factors like blood oxygen.

Because LEDs can't accurately track glucose information, Know Labs had to go "further out on the electromagnetic spectrum," the company's CEO Ron Erickson told CNET. He said that, while a medical-grade device is likely the first step for the company, he's not opposed to opening up the patented technology to consumer wearable devices.

Calling Know Labs' technology "form-factor agnostic," Erickson wants glucose tracking to feed health trends -- which is the whole point of consumer wearables that give you health trends. 

"My longer vision, beyond glucose, is predictive health," he said.