Beyond Glucose: The FDA Just Opened the Door to Continuous Ketone Monitoring

For years, continuous glucose monitors have changed the way many people think about metabolism.

Instead of seeing a single fasting glucose value at a physical—or even an occasional finger-stick—CGMs made it possible to watch glucose change throughout the day: after meals, during exercise, overnight, during illness, and in response to everyday behavior.

Now another metabolic signal is becoming continuous.

On August 25, 2026, the U.S. Food and Drug Administration authorized Abbott's Libre Duo 10 Day Continuous Dual Glucose Ketone Monitoring System for people aged 2 years and older living with diabetes.

According to the FDA, it is the first wearable device authorized in the United States to continuously monitor ketones and the first device globally to continuously monitor both glucose and ketones using a single wearable sensor.

That distinction matters.

But perhaps not for the reason the longevity and biohacking world might initially assume.

This is primarily a diabetes-safety breakthrough

Ketones have become closely associated with ketogenic diets, fasting and metabolic optimization.

Clinically, however, ketone monitoring can serve a very different—and far more urgent—purpose.

When insulin is insufficient, the body can rapidly increase production of ketones. In people with diabetes, excessive ketone accumulation can contribute to diabetic ketoacidosis, or DKA, a potentially life-threatening metabolic emergency.

Until now, ketone measurements have generally required separate blood or urine testing, producing individual snapshots.

The newly authorized system measures glucose and ketones in the fluid beneath the skin every minute, transmitting the results to a compatible smartphone and showing whether the values are rising or falling. It can also provide alerts when ketones reach concerning levels.

That changes the information available to a patient and clinician.

A reading tells you where a biomarker is.

A trend can begin to tell you where it is going.

And in rapidly developing conditions such as DKA, the difference can be clinically meaningful.

Why glucose alone does not always tell the entire story

One particularly important concept is euglycemic diabetic ketoacidosis.

DKA is commonly associated with very high glucose, but the American Diabetes Association notes that approximately 10% of people presenting with DKA may have glucose below 200 mg/dL.

Certain circumstances—including reduced food intake and use of SGLT2 inhibitor medications—can contribute to DKA occurring without the extreme glucose elevation people may expect.

That is one reason simultaneously watching glucose and ketones is potentially more informative than watching glucose alone.

The ADA's 2026 Standards of Care specifically anticipated that continuous ketone monitoring could eventually offer a new approach to helping prevent DKA in people at risk.

Less than a year later, the first such device has now received FDA marketing authorization.

The technology had already begun producing encouraging clinical data

Continuous ketone monitoring is not simply an engineering concept.

Earlier this year, researchers published results from a prospective multicenter study examining continuous ketone monitoring in adults being treated for DKA at two U.S. emergency departments.

Thirty-four patients participated.

Continuous measurements of beta-hydroxybutyrate—the primary ketone measured clinically in DKA—showed a strong correlation with venous blood measurements.

Researchers reported a correlation coefficient of 0.96, and the continuous system identified resolution of DKA an average of 55 minutes earlier than standard care in the study.

That does not prove that every continuous ketone monitor will improve clinical outcomes, nor does a relatively small feasibility study settle the question.

But it illustrates why continuous measurement may be valuable.

A biological process is dynamic.

Our traditional method of measuring it usually is not.

The bigger shift: from measurements to trajectories

This may ultimately be the most important part of the story.

Modern medicine has historically relied heavily on snapshots.

A blood draw might show:

• glucose at 8:12 a.m.
• triglycerides at 8:12 a.m.
• cortisol at 8:12 a.m.
• inflammatory markers at 8:12 a.m.

These measurements can be extremely valuable.

But human physiology does not exist only at 8:12 a.m.

Metabolism changes after meals.

Glucose changes during sleep.

Heart rate changes with stress.

Blood pressure changes throughout the day.

Ketones change with insulin availability, illness, fasting, nutrition and energy metabolism.

Continuous sensors add another dimension to health data: time.

Instead of simply asking, "What is the number?" we can increasingly ask:

• What is the pattern?
• How quickly is it changing?
• What happened before it changed?
• Does the change repeat?

Those questions can sometimes be more informative than another isolated measurement.

More data is not automatically better medicine

There is an important counterpoint.

Continuous measurement can create the illusion that every fluctuation requires intervention.

It does not.

Human physiology is supposed to fluctuate.

A glucose rise after eating is not inherently pathological.

The presence of ketones is not inherently dangerous.

And a wearable-generated abnormality does not automatically establish a diagnosis.

The FDA itself emphasizes that ketone information from the new system should be interpreted alongside glucose readings and symptoms.

That principle extends far beyond this particular device.

Advanced testing is most useful when the measurement has:

• sufficient analytical accuracy,
• a meaningful biological relationship,
• appropriate clinical context, and
• an actionable reason for being measured.

Without those pieces, greater amounts of data can simply produce greater amounts of noise.

What this does—and does not—mean for metabolic optimization

It would be easy to interpret the Libre Duo announcement as the beginning of continuous ketone tracking for everyone interested in fasting, ketogenic diets or metabolic health.

The evidence does not support making that leap yet.

The FDA authorization announced August 25 applies to people living with diabetes. It is a diabetes device, not an over-the-counter consumer wellness product such as Lingo or Stelo.

The clinical rationale is principally the recognition of rising ketones and the potential for earlier identification of dangerous metabolic changes.

That is very different from demonstrating that continuous ketone monitoring improves health, longevity, fat loss or athletic performance in otherwise healthy adults.

Those questions require their own research.

A biomarker becoming measurable does not automatically make optimizing that biomarker beneficial.

That distinction is increasingly important as health technology gives consumers access to more biological information than ever before.

Where this gets interesting next

Continuous glucose monitoring established that people could realistically collect metabolic information around the clock outside a hospital.

Continuous glucose-plus-ketone monitoring expands that concept.

And it raises a larger question:

How many clinically useful signals will eventually move from occasional testing to continuous—or near-continuous—measurement?

We are already seeing rapid development in wearable and minimally invasive sensing for cardiovascular signals, glucose, temperature, oxygenation and other biomarkers.

The long-term opportunity is not necessarily a future in which people stare at dozens of numbers all day.

The more compelling future is one in which technology quietly collects high-quality physiological data, software identifies meaningful changes, and clinicians receive better information when a decision actually needs to be made.

In other words: measure more, interrupt less, understand better.

The FDA authorization of the Libre Duo is primarily an important advancement for diabetes care.

But it may also represent something larger.

Health testing is beginning to evolve from occasional pictures of the body into something closer to a movie.

The challenge now is making sure that our ability to collect biological data advances alongside our ability to understand what that data actually means.

The Modern Bio Take

The future of advanced health testing is unlikely to be defined simply by ordering more tests.

It will be defined by identifying the right signals, measuring them at the right frequency, and interpreting them in the context of the individual.

Continuous ketone monitoring is a strong example: highly meaningful for specific clinical situations, technologically impressive, and potentially a foundation for broader metabolic sensing—but not yet evidence that everyone should continuously track ketones.

Better measurement should ultimately lead to better decisions, not simply more numbers.

Educational note: This article is for general educational purposes and is not medical advice. Wearable data and laboratory results should be interpreted in the context of an individual's medical history, symptoms and other clinical information. Diagnosis and treatment decisions remain the responsibility of the patient and their qualified healthcare practitioner.

Sources

• U.S. Food and Drug Administration — August 25, 2026: FDA authorization of the Libre Duo 10 Day Continuous Dual Glucose Ketone Monitoring System.
• American Diabetes Association — Standards of Care in Diabetes 2026: Hyperglycemic crises, ketone monitoring and the potential role of continuous ketone monitoring.
• Haas et al., Diabetes Technology & Therapeutics, 2026: Prospective multicenter study of continuous ketone monitoring during diabetic ketoacidosis.