Abbott’s new Libre Duo continuously measures glucose and ketones together. It was developed for diabetes, but its significance extends much further.
I’ve been thinking about ketones a lot lately.
This past July, my dad, my son Jacob and I traveled to Boston College to spend a day in Professor Thomas Seyfried’s laboratory. Much of our conversation centered on cancer metabolism, nutritional ketosis, and the importance of knowing what is actually happening with the glucose and ketones inside the body.
This isn’t a new subject for us. Seyfried’s landmark book, Cancer as a Metabolic Disease, was published in 2012. My father, Ralph Moss, reviewed it the following year and first visited Seyfried’s laboratory in 2014. More than a decade later, we returned together, three generations of Mosses, to see where that research stands today.
Through my work at The Moss Report, I’ve continued exploring metabolic health and cancer with Seyfried and others, including mitochondrial researcher Christos Chinopoulos, How to Starve Cancer author Jane McLelland, and metabolic-health leader Dr. Nasha Winters. I recently recorded an upcoming podcast with University of South Florida professor Dominic D’Agostino, whose research has extensively explored ketone metabolism and therapeutic ketosis.
Last year, at the Metabolic Health Day Conference in Tucson, I also met Dorian Greenow, founder of Keto-Mojo. His presentation was titled “Metabolic Interventions: The Power of Ketone Testing and a Continuous Remote Care Model.” Greenow is now scheduled to join us for an upcoming Moss Report podcast as well. I’m looking forward to that conversation.
So when I saw what the FDA had just authorized, it immediately got my attention.
Meet the Libre Duo
On August 25, 2026, the FDA authorized the first wearable device in the United States capable of continuously monitoring ketones and the first device in the world capable of continuously measuring both glucose and ketones through a single sensor.
That may sound like another incremental advance in wearable health technology, but in my opinion, it’s a very big deal.
The FDA-authorized device is Abbott’s Libre Duo 10 Day Continuous Dual Glucose Ketone Monitoring System.
It is authorized for people aged two and older living with diabetes. A small wearable sensor measures glucose and the ketone beta-hydroxybutyrate, or BHB, in the interstitial fluid just beneath the skin. It measures both every minute, day and night, and sends the readings wirelessly to a compatible smartphone.
The FDA reviewed six clinical studies involving more than 600 participants. According to the agency, the device was able to track clinically meaningful differences in ketone levels over its 10-day wear period and identify elevated ketones before the onset of diabetic ketoacidosis, or DKA.
That is the immediate reason this device exists.
For someone with diabetes, particularly someone who does not have enough insulin, rising ketones can signal a potentially life-threatening metabolic emergency. Importantly, glucose and ketones do not always move in the same direction. Someone can have dangerously elevated ketones even when glucose does not appear extraordinarily high.
Until now, ketone testing generally meant stopping to perform a separate blood or urine test. That gives you a measurement at one moment in time. It doesn’t necessarily tell you where your ketones were an hour earlier or where they’re heading next.
Libre Duo changes that.
https://www.freestyle.abbott/us-en/products/libre-duo-coming-soon.html
Ketones Aren’t Just About Diabetes
For generations, many people learned about ketones primarily in the context of diabetes and ketoacidosis.
But that’s only one side of ketone metabolism.
When carbohydrate availability falls sufficiently, the liver begins converting fatty acids into molecules collectively called ketone bodies. They provide an alternative energy source when glucose availability is reduced, as happens during fasting and carbohydrate-restricted ketogenic diets.
There are three principal ketone bodies: acetoacetate, beta-hydroxybutyrate and acetone.
Acetoacetate is produced first. It can then be converted into BHB, the predominant ketone commonly measured in blood during nutritional ketosis, or break down into acetone, which is expelled largely through the breath.
And yes, acetone really is acetone. It’s the same chemical, CH3COCH3, familiar as the principal solvent in traditional nail-polish remover. That’s one reason people in substantial ketosis can sometimes develop the characteristic fruity or slightly solvent-like “keto breath.” The body is producing acetone and exhaling some of it through the lungs.
BHB is particularly interesting because it is more than simply another fuel. It is also a biologically active signaling molecule, with documented effects on pathways involving inflammation, oxidative stress, gene expression and cellular metabolism.
That doesn’t mean ketones cure disease. It does help explain why researchers have become increasingly interested in what happens when we deliberately shift the body from predominantly glucose-based metabolism toward greater reliance on fat and ketones.
And that brings us to nutritional ketosis.
This is fundamentally different from diabetic ketoacidosis. DKA is a pathological state generally involving insulin deficiency and uncontrolled ketone production. Nutritional ketosis is a controlled physiological state in which BHB rises much more modestly while the body’s normal acid-base regulation remains intact.
Same family of molecules. Very different metabolic situation.
The Growing Interest in Nutritional Ketosis
Ketogenic diets are certainly not new. Their therapeutic use in epilepsy goes back more than a century.
What has changed is the breadth of interest.
Ketogenic and very-low-carbohydrate diets are now widely used for weight loss and metabolic health, and ketogenic metabolic interventions are being studied in diabetes, metabolic syndrome, neurological disease, PCOS, cancer and other conditions. The strength of evidence varies considerably among these applications, and some remain decidedly experimental.
But the metabolic-health movement has pushed an important idea into the mainstream:
Following a ketogenic diet and actually achieving nutritional ketosis are not necessarily the same thing.
You can eat foods labeled “keto.” You can eliminate bread and pasta.
That doesn’t necessarily tell you what is happening metabolically.
If nutritional ketosis is the objective, eventually you need to measure whether you’re actually achieving it.
This was one of the things that struck me during Dorian Greenow’s presentation at Metabolic Health Day.
One of his slides carried the headline:
KETONES ARE MORE THAN FUEL!
Another showed ketogenic metabolic interventions in relation to metabolic syndrome, diabetes, cardiovascular risk, epilepsy, weight reduction, neurological disease, PCOS and cancer.
Again, the evidence is not equally strong for every condition on that list. But Greenow’s larger point about measurement was compelling.
If you’re deliberately trying to change your metabolism, wouldn’t you want to know whether you’re succeeding?
“The GKI Will Tell Them Where They Are”
That same question came up repeatedly when we visited Seyfried’s laboratory in July.
Seyfried’s work focuses on cancer, but the principle is much broader. He doesn’t simply want someone to say that they’re eating a ketogenic diet. He wants to know what that diet is actually doing to their metabolism.
At one point during our conversation, he put it about as simply as possible:
“The GKI will tell them where they are.”
GKI stands for Glucose Ketone Index. Seyfried and his colleagues proposed it more than a decade ago as a way of expressing the relationship between blood glucose and BHB rather than considering either measurement in isolation.
The calculation itself is simple, and you don’t need any special equipment beyond glucose and blood ketone readings. To calculate GKI, first divide glucose in mg/dL by 18 to convert it to mmol/L, then divide that number by your BHB level in mmol/L. For example, a glucose reading of 90 mg/dL and BHB of 1.5 mmol/L gives a GKI of 3.3. Keto-Mojo also provides a free online calculator that does the math for you:
https://keto-mojo.com/glucose-ketone-index-gki/
The GKI has become particularly associated with Seyfried’s proposed metabolic approach to cancer.
During our visit, Seyfried essentially told us: Don’t ask me what you should eat. Eat something and see what it does to the meter.
And of course, Seyfried is correct on this point. We are individuals. The same meal can produce different glucose responses in different people. Exercise, sleep, fasting, stress, medications and a host of other variables can affect metabolism.
So rather than relying entirely on a dietary rulebook, look at what your own body is doing.
From a Snapshot to a Movie
Continuous ketone monitoring itself isn’t entirely new. SiBio already offers a wearable sensor that continuously tracks ketones. What makes Abbott’s Libre Duo different is that it continuously measures both glucose and BHB through a single sensor, allowing us to see the relationship between the two in real time.
For the most part, people interested in measuring nutritional ketosis have generally used finger-stick blood testing.
Keto-Mojo is probably the best-known example. Its meter measures both blood glucose and BHB and calculates GKI. I’ve followed their work for years, and meeting Greenow in Tucson gave me an even greater appreciation for the value of actually measuring these variables.
But a finger stick is still a moment in time.
Maybe you test when you wake up. Maybe you test before dinner or a couple of hours after eating.
What happened during all the hours in between?
That’s what makes continuous monitoring so interesting.
Imagine being able to see what happens to glucose and ketones after a particular meal. What happens overnight? What happens during a fast? What happens after exercise? How quickly do you move into ketosis and, perhaps more importantly, what knocks you back out.
A finger stick gives you a snapshot.
Continuous monitoring gives you the movie.
And I think that could change the way we think about metabolic interventions.
It could also improve research. “Following a ketogenic diet” is not actually a metabolic measurement. Two people assigned to the same diet may achieve very different levels of ketosis.
With continuous data, researchers could potentially begin asking more interesting questions: How much time did someone actually spend in nutritional ketosis? How did glucose and BHB interact over the course of the day? Did greater metabolic exposure correspond with a particular outcome?
Those are much richer questions than simply asking whether someone was assigned to the ketogenic-diet group.
FDA Has Authorized the Measurement, Not the Therapy
There is an important distinction to make here.
The FDA has not declared nutritional ketosis a treatment for metabolic disease, cancer or anything else.
Abbott’s Libre Duo was developed for diabetes. That’s the indication FDA reviewed, and that’s the use for which it has been authorized.
But I still think the authorization represents something important for the broader metabolic-health movement.
Ketones have become medically important enough that the FDA has authorized a device to measure them continuously, around the clock, alongside glucose.
In other words, glucose alone does not always provide enough information about someone’s metabolic state.
Ketones matter too.
People pursuing nutritional ketosis have already figured this out. They’re buying meters, pricking their fingers, measuring BHB, tracking glucose and calculating GKI because they want to know whether their dietary interventions are actually changing their metabolism.
Abbott didn’t invent that idea.
What Abbott has done is take it to the next technological level.
The FDA has legitimated the measurement, not the therapy.
That’s an important distinction, but it’s also an important milestone.
Why I’m Particularly Interested in the Cancer Question
My own route into this subject has largely been through cancer.
The metabolic theory of cancer proposes that abnormalities in cellular energy metabolism, particularly involving mitochondrial function and dependence on fermentable fuels such as glucose and glutamine, may play a fundamental role in the disease.
That remains controversial, and translating these ideas into successful human cancer treatment is still very much a work in progress.
But one thing I’ve learned from Seyfried, Chinopoulos, D’Agostino and others working in this field is that simply saying someone is “on a keto diet” tells us very little.
During our July visit, Seyfried’s senior scientist Purna Mukherjee emphasized that in their experimental work, merely raising ketones without adequately controlling glucose does not produce the desired effect. Seyfried repeatedly came back to the relationship between the two.
That is why the ability to continuously measure both glucose and BHB simultaneously immediately caught my attention.
Whether continuous dual monitoring ultimately proves useful in metabolic cancer research remains to be seen.
But now we have the tool.
You Can’t Buy One Yet
Unfortunately, there’s a catch.
As of this writing, Abbott says Libre Duo is “coming soon” in the United States.
https://www.freestyle.abbott/us-en/products/libre-duo-coming-soon.html
And when it arrives, the current FDA-authorized indication is diabetes. Federal law restricts the device to sale by or on the order of a physician.
https://www.freestyle.abbott/us-en/safety-information.html
So this is not, at least initially, an over-the-counter metabolic-health wearable that anyone experimenting with nutritional ketosis can simply order.
Will that eventually change? I certainly hope so.
Given the enormous interest in continuous glucose monitoring, ketogenic diets and metabolic health, I would be surprised if the broader health community didn’t become extremely interested in continuous glucose-and-ketone monitoring.
The technology is simply too interesting.
What We Can and Can’t Do Now
Fortunately, you don’t need to wait for Abbott if you want to know what your glucose and ketones are doing.
Keto-Mojo already provides finger-stick measurement of both glucose and BHB and automatically calculates GKI. It isn’t continuous, but it allows you to begin measuring your own metabolic response right now.
Readers who want to try it can save 10% on eligible Keto-Mojo ketone meter kits through this affiliate link:
Did HHS Help Push Through Approval?
There’s one other aspect of the timing that I find interesting.
The current leadership at HHS has placed unusual emphasis on nutrition, chronic disease and metabolic health through the Make America Healthy Again initiative. At the same time, the FDA has emphasized bringing more health technology into the home.
I have emailed to ask the HHS whether its increased emphasis on metabolic health played any role in encouraging, prioritizing or facilitating the development or review of continuous ketone-monitoring technology. I haven’t heard back thus far.
I don’t know that there is a connection between HHS initiatives and this FDA approval, but the timing is certainly interesting.
And regardless of the politics, the larger movement toward giving people more information about their own metabolic health is something I enthusiastically support.
I’m Going Keto
There’s also a personal reason I’m excited about all of this.
I’ve gone keto before, and I had amazing results. I lost weight, had lots of energy, felt great and experienced firsthand just how dramatically the body can respond when you change what you’re feeding it. But, like many people, eventually I drifted away from it.
I’ve decided it’s time to do it again. I’m going keto. And this time I want to measure it properly.
I want to see what happens to my glucose, my BHB and my GKI. I want to know how quickly I can move into nutritional ketosis, how consistently I can stay there, which foods work for me and which don’t, and what happens to my weight, energy and other markers of metabolic health along the way.
When continuous glucose-and-ketone monitoring becomes available, you can be pretty certain I’ll be one of the first in line.
After years of reporting on metabolism, I’m looking forward to putting some of this into practice again myself, and I’ll let you know what happens.
Because for all the theories, diets, arguments and competing ideas about metabolic health, there is something wonderfully straightforward about this new generation of technology. Real-time glucose and ketone monitoring may just be the kickstart our society needs to get metabolic function under control. And boy, do we need that.
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