This report concerns a serious, life-threatening CGM failure with no malfunction warning.
I am a 47-year-old Type 1 diabetic with 45 years of disease management experience and a new Dexcom G7 user.
On February 28 at 7:30 p.m., I inserted a new sensor. The device paired, warmed up, and reported normally. There were no errors or alerts indicating inaccurate readings.
Overnight, the device repeatedly alarmed “EXTREMELY LOW.” Following standard diabetes safety protocols, I treated each alarm with sugar. This occurred hourly throughout the night.
By morning, despite zero symptoms of hypoglycemia, the device continued alarming. Before eating, I manually tested my blood glucose.
The result was 31.8 mmol/L fasting — a level associated with risk of coma and loss of consciousness.
This confirms the device delivered critically incorrect readings for hours, actively prompting behavior that worsened a dangerous condition.
This failure occurred:
• Without malfunction alerts
• Without accuracy warnings
• Without user-detectable indication
This constitutes a silent failure mode with severe patient safety implications, especially during sleep.
Offering sensor replacement does not address the seriousness of this event. This incident requires formal investigation, not customer service resolution.
CGMs are relied upon for life-preserving decisions. A device that can fail in this manner without warning represents a systemic safety risk.
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