For people living with diabetes, glucose is only one part of the safety picture. Ketones can rise when the body does not have enough usable insulin, and a dangerous buildup can progress toward diabetic ketoacidosis (DKA). On August 25, 2026, the U.S. Food and Drug Administration authorized the first wearable in the United States designed to continuously monitor ketones and glucose together. This article explains what the authorization covers, what the device may add to diabetes care, and why a new stream of data does not replace a personal sick-day plan or urgent medical evaluation.
What the FDA authorized
The FDA authorized the Libre Duo 10 Day Continuous Dual Glucose Ketone Monitoring System for people age 2 years and older who live with diabetes. According to the agency, it is the first U.S. wearable to continuously monitor ketones and the first device worldwide authorized to monitor glucose and ketones together in one system. A sensor measures both substances in fluid just beneath the skin and sends readings to a compatible smartphone.
The agency used the De Novo pathway, which is intended for new types of low- to moderate-risk devices. The authorization also establishes special controls covering areas such as labeling and performance testing. That regulatory decision is important, but it is not the same as a guarantee that every reading will be correct or that every episode of DKA will be prevented.
| FDA announcement detail | What it means | What it does not mean |
|---|---|---|
| Glucose and ketones measured together | Users can see two related trends from one wearable system | One number can be interpreted without symptoms or clinical context |
| Readings transmitted to a smartphone | Trends and alerts may be viewed without a separate handheld reader | Phone settings and connectivity can be ignored |
| Authorized for ages 2 and older with diabetes | The reviewed indication includes children and adults | The device is appropriate for every individual or every treatment plan |
| Ten-day wear period | The sensor is designed to collect repeated measurements over ten days | A sensor lasts indefinitely or needs no replacement |
Why continuous ketone information matters
Ketones are produced when the body uses fat for energy. Small amounts can occur in several circumstances, but a rapid buildup in someone with diabetes can signal insufficient insulin and possible DKA. The Centers for Disease Control and Prevention describes DKA as serious and potentially life-threatening, most commonly affecting people with type 1 diabetes, although people with type 2 diabetes can develop it as well.
Traditional home ketone checks generally provide a single measurement using blood or urine. A continuous sensor adds direction: whether a measured level appears stable, rising, or falling. That trend may help a person notice a developing problem earlier, especially during illness or after a suspected interruption in insulin delivery. The FDA says the new system measures every minute and can provide automatic alerts at a concerning ketone threshold.
Continuous ketone data may make a hidden change easier to see, but the value comes from combining the trend with symptoms, glucose data, device instructions, and a clinician-approved response plan.
How the dual sensor works
Measurements come from interstitial fluid
The wearable sensor sits under the skin and measures glucose and ketones in interstitial fluid rather than drawing blood continuously. These values can be clinically useful, but they are not identical to a laboratory blood measurement at every moment. Rapid biological changes, sensor performance, placement, and other factors can affect how a reading relates to what is happening in the bloodstream.
The smartphone shows values, direction, and alerts
Readings are sent wirelessly to a compatible phone. The display can show current values and whether they are moving up or down. That creates a practical advantage over isolated measurements, but it also creates a dependency on the phone, operating system, app permissions, volume, Bluetooth connection, and notification settings.
A dual trend is not an automated diagnosis
The device can identify data patterns; it cannot independently diagnose the cause of nausea, vomiting, fatigue, breathing changes, or abdominal pain. Ketone information should be interpreted alongside glucose and symptoms. A person may also need a confirmatory test or professional evaluation according to the device labeling and their individualized care plan.
| Data source | Strength | Important limitation |
|---|---|---|
| Continuous glucose trend | Shows direction and repeated glucose readings | May lag or disagree with symptoms during rapid change |
| Continuous ketone trend | May reveal a rise between spot checks | Is new technology with limited real-world experience |
| Blood or urine spot test | Provides a familiar check at a specific time | Does not show what happened between tests |
| Symptoms and clinical assessment | Adds the human and medical context | Cannot be replaced by an app or wearable alert |
What the evidence reviewed by the FDA showed
The FDA reports that the sponsor submitted clinical and performance data from six studies involving more than 600 participants age 2 years and older. The studies evaluated glucose and ketone accuracy across different concentration ranges. The agency says the device tracked clinically meaningful differences in ketone levels during the ten-day wear period and identified elevated ketones before DKA developed in study observations.
This evidence was sufficient for marketing authorization under the De Novo pathway. It does not answer every question about long-term outcomes. The FDA announcement does not claim that continuous ketone monitoring eliminates DKA, reduces hospitalizations by a specified percentage, or is superior for every patient. Those broader outcomes will require continued clinical experience and research.
A 2024 peer-reviewed review in Diabetes, Obesity and Metabolism described continuous ketone monitoring as a promising emerging tool and discussed potential clinical applications. The operative word is emerging: enthusiasm about a new capability should remain separate from evidence about outcomes after widespread use.
Who may find the added data most relevant
The authorized population is broad, but the practical value is likely to differ. People with type 1 diabetes, caregivers of young children, insulin-pump users, and people who have previously experienced DKA may have particular reasons to discuss continuous ketone monitoring with a diabetes clinician. Illness, vomiting, missed insulin, and pump interruption are familiar situations in which ketone awareness matters.
Some people with type 2 diabetes also face DKA risk, including in specific clinical circumstances. Medication decisions and ketone plans are individualized. The presence of a wearable does not justify changing insulin, other diabetes medicine, carbohydrate intake, or hydration without the guidance already provided by a qualified professional.
Medical safety note: anyone considering a new monitoring system should review its indication, compatibility, alert settings, backup testing instructions, costs, and response plan with the diabetes care team.
What users and caregivers still need to do
A sensor can reduce the burden of repeated spot checks, but it introduces a different kind of work: keeping the system functioning and knowing what to do when the data and the body tell different stories. A practical setup conversation should cover the following:
- Which ketone and glucose alerts should be enabled and which must remain audible.
- What to do if a reading does not match symptoms or a sensor error appears.
- Which backup blood or urine ketone supplies should remain available.
- How illness, vomiting, missed insulin, or pump problems change the response plan.
- Who to contact for routine questions and when urgent care is necessary.
The FDA previously warned that smartphone-compatible diabetes devices can miss critical alerts because of notification permissions, focus modes, connected audio accessories, unsupported operating-system updates, or other settings. That warning applies to the broader category of connected diabetes technology and is especially relevant when an alert is expected to prompt safety action.
| Check | When to do it | Reason |
|---|---|---|
| Confirm app and phone compatibility | Before setup and before an operating-system update | Unsupported software can affect device operation or alerts |
| Review notification and volume settings | At setup and periodically | Focus modes or audio routing may silence an alert |
| Keep approved backup testing available | Throughout sensor use | A sensor can fail or disagree with symptoms |
| Review the sick-day plan | Before illness occurs | Decisions are harder to make during a rapidly changing situation |
A safe way to respond to unexpected readings
The device instructions and an individualized diabetes plan should control the response. A general sequence for discussing preparedness with a clinician is:
- Notice the glucose value, ketone value, trend arrows, alerts, and any symptoms together.
- Check that the sensor and phone appear to be working and that the data are current.
- Use the approved backup test specified in the labeling or care plan when results seem inconsistent.
- Follow the personal sick-day or ketone plan supplied by the diabetes care team.
- Seek urgent help for severe symptoms or thresholds identified in that plan.
Urgent safety note: trouble breathing, repeated vomiting with inability to keep fluids down, fruity-smelling breath, confusion, or multiple DKA symptoms require immediate medical attention. Do not wait for a wearable trend to resolve or use this article to make treatment decisions.
What the device cannot replace
More data can create false reassurance if a person assumes an absence of alerts means an absence of risk. It can also create alarm fatigue if thresholds are poorly configured or if users receive frequent notifications they do not understand. Training, labeling, and support remain part of safe use.
The dual monitor does not replace prescribed insulin, a backup meter, clinician-directed ketone testing, or emergency care. It also should not be confused with unauthorized smartwatches or rings that claim to measure glucose without piercing the skin. The FDA has specifically warned that it has not authorized watches or rings that independently measure or estimate glucose noninvasively.
Questions to ask before adopting a dual monitor
Because the technology is new, a short checklist can make a clinical conversation more concrete:
- How should this device fit with my current glucose monitor, insulin delivery system, and backup tests?
- Which symptoms or trend combinations should prompt a confirmatory check?
- What are the approved alert thresholds and what action belongs with each alert?
- What happens when the phone is unavailable, the sensor loses connection, or an update changes permissions?
- What training and customer support are available for caregivers, school staff, or other helpers?
Cost, insurance coverage, phone compatibility, skin tolerance, data sharing, and replacement supplies may also affect whether the system is practical. Authorization establishes that the device met the FDA’s requirements for its intended use; it does not make the device universally necessary.
Bottom line
The FDA’s August 25 authorization marks a meaningful shift in diabetes monitoring: glucose and ketone trends can now be collected continuously through one authorized wearable system for people age 2 and older with diabetes. The added trend may help users and caregivers notice rising ketones sooner than periodic testing alone. The strongest interpretation remains measured. Continuous data are an additional safety tool, not a diagnosis, a guarantee against DKA, or a replacement for symptoms, backup testing, a clinician-approved plan, and urgent care when warning signs appear.
Sources
- U.S. Food and Drug Administration: authorization of the first continuous glucose-ketone wearable
- Centers for Disease Control and Prevention: diabetic ketoacidosis
- U.S. Food and Drug Administration: smartphone-compatible diabetes device alert safety
- U.S. Food and Drug Administration: warning on unauthorized watches and rings for glucose measurement
- U.S. Food and Drug Administration: blood glucose monitoring devices
- PubMed: Continuous ketone monitoring – exciting implications for clinical practice
