Imagine relying on a continuous glucose monitor (CGM) app to track your blood sugar—only to have the sensor fail and the app quietly stop sending data. You see the “No active sensor” screen and assume everything is OK or that it’s just a small glitch. But it’s not. Because the app didn’t alert you to a serious hardware/firmware failure that cut off data and alarms.
That’s what prompted Dexcom, with support from the FDA, to issue a mandatory correction for certain versions of its G7 and ONE+ CGM apps. This issue could lead to undetected prolonged hypoglycemia or hyperglycemia—potentially dangerous, especially for insulin users.
What Happened — The Correction
Here are the facts, per the FDA announcement: U.S. Food and Drug Administration
- Affected Products
Dexcom G7 and Dexcom ONE+ apps, on Android, iOS, and watchOS platforms. U.S. Food and Drug Administration
Specific versions affected:
• G7 Apps version 2.8.0 or earlier
• ONE+ apps version 1.4.0 or earlier U.S. Food and Drug Administration - What the Design Error Is
There is a software design flaw that causes the app not to alert the user when the sensor’s transmitter experiences a hardware or firmware failure. Instead of triggering a “Sensor Failed” alert, the session ends and the app shows a “Start Sensor” screen or “No active sensor” message—without notifying that something has gone wrong under the hood. U.S. Food and Drug Administration - Why This Is Important
Because of this, significant periods of glucose data can be lost without the patient knowing. Alerts, alarms, notifications stop. This could lead to delayed treatment for dangerous lows (hypoglycemia) or highs (hyperglycemia), which in turn risks serious injury or death. U.S. Food and Drug Administration - What Dexcom & Users Must Do
• Update the app immediately if you are on versions ≤ those specified. After August 20, 2025, versions 2.8 or earlier (for G7) and 1.4 or earlier (for ONE+) will not be usable. U.S. Food and Drug Administration
• Install the latest version from the App Store / Google Play, then reopen the app. U.S. Food and Drug Administration - Severity
The FDA classifies this correction as among the most serious types, meaning there is potential for serious injury or death if uncorrected. U.S. Food and Drug Administration - Reported Harm
No injuries or deaths have been reported yet linked to this issue. U.S. Food and Drug Administration
Why This Matters
This isn’t just a routine app bug. For people depending on CGMs, especially the elderly, children, or those with impaired awareness of symptoms, continuous and reliable glucose values + alerts are life-critical.
- Safety Risks from Missing Alerts
Without alerts, users may not realize they’ve gone long periods without glucose data. For example, overnight highs or lows may go unnoticed, leading to complications or more immediate risks. - Trust & Reliability
Wearable/remote/IoT health devices span hardware, firmware, software, connectivity. A failure in any link—especially alerting—can undermine confidence in the whole system. For patients and clinicians, reliability is non-negotiable. - Regulatory Implications
This incident underscores the importance the FDA places on software design, not just hardware. Apps are medical devices now; their software must anticipate failures and provide safe fallback behaviors (e.g. notifying users). - Broader Lessons for Digital Health
• Version control and update deployment are vital—users should get updates quickly.
• Monitoring app performance & user feedback continuously (post-market surveillance) is necessary.
Additional Context & Technical Details
Here are some extra details and interpretations to deepen understanding:
- Why the “Sensor Failed” Alert Matters
A CGM system not only tracks glucose, it alerts for extremes. Without “sensor failure” alerts, one might believe everything is normal—even when data flow has stopped. This can be dangerous during sleep or when user is busy. - How Apps & Sensors Interact
Sensors (hardware/firmware) detect glucose, transmit to the app. If transmitter fails, the pathway breaks. Apps are supposed to monitor this state and alert when transmitter/sensor fails—this is part of safety design. - Updated Versions will Fix/Improve
The fix likely involves adding explicit detection of transmitter/sensor failure and generating alerts/alarms so users are aware of loss of signal. Also, ensuring users can’t ignore or bypass those messages unknowingly. - Impacted Population
People with diabetes using Dexcom G7 or ONE+ who rely on their smartphone or watch instead of just the receiver. Those using older versions are most at risk until they update. - Timing
The deadline (August 20, 2025) is important. After that, the old versions will be disabled (i.e. not usable). So users must update well before then to avoid being caught off guard.
What Users Should Do
If you or someone you know uses Dexcom G7 / ONE+ via app:
- Check your app version right away.
• On Android / iOS / Watch: go to settings → about / app info. - If version is ≤ 2.8.0 (for G7) or ≤ 1.4.0 (ONE+), update immediately to the newest version.
- Verify after update that alerts are working properly. Maybe test a scenario (if safe) where the sensor is removed or disconnected to see if app indicates sensor failure.
- Talk to your clinician if you have concerns—for example, if you noticed periods without data in the past.
- Consider backup: have alternate means of monitoring if you suspect app issues (receiver, other trusted devices).
Implications for the Industry & Future Considerations
- Software Quality Assurance (SQA) & Validation in Medical Apps
Manufacturers must build in more robust detection of hardware/firmware failures and test fail-safe behaviors. - User Interface / UX Design
It’s not enough to design for ideal situations; the app must handle worst-case scenarios (sensor failure, transmitter issue) in a way that’s obvious to users. - Regulatory Oversight of Health Apps
As more health devices depend on apps, regulators will likely pay more attention to software design and post-market update behaviors. - Updates & Version Management
Ensuring users are compelled to update (or at least strongly prompted), automatic updates where possible, and managing legacy versions to avoid safety gaps. - Patient Education
Users need to understand what to do if alerts stop, or if they see “No active sensor” — not to assume the device is just “idle” but to check for updates or sensor issues.
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