Is it me or do others think these sensors, for those who cannot get for free, are a complete rip off.
At £50 a pop I think so. The manufacturing cost must be so minimal. I took one apart to have a look
not much to see there a small circuit board and a plastic outer. I was interested in the NFC chip it contains.
This chip has a deliberate timer of 15 days programmed into it whereas it could go on possibly for many
months if programmed so. The chip in question does not respond to an NFC chip reset program, a real pity.
I know a bit about this.
The moment you insert a CGM, your immune system treats the microscopic filament as an invading hostile object.
First Days of Use: Your body sends inflammatory cells to investigate the CGM.
Later Days of Use: Your body's cells begin trying to wall off the sensor, coating it in a microscopic layer of protein, tissue, and bio-fouling (like barnacles on a the hull of a boat).
The Result: This cellular wall physically blocks glucose in your interstitial fluid from reaching the sensor's chemistry. If left in place too long, the readings drift drastically, which can lead to life-threatening errors in insulin dosing.
Most mainstream CGMs rely on an electrochemical reaction using an enzyme called '
glucose oxidase.'
This enzyme actively breaks down glucose molecules to generate the tiny electrical current your CGM measures.
Enzymes are fragile biological proteins. Over 10 to 15 days of continuous exposure to body heat, moving fluids, and metabolic waste, the chemistry literally degrades and burns out.
15 days is pushing the limits of 'medical-grade' adhesives exposed to daily showers, sweat, friction, and skin oils. Studies show that a primary cause of late-stage sensor failure isn't even the technology inside, but simply the tape peeling off or losing grip.
Keeping an active puncture wound covered in a damp, sweaty adhesive patch for longer than 15 days also exponentially increases the risk of severe skin irritation, contact dermatitis, and bacterial infection.
So why do CGM apps force a shutdown exactly at day 10 or 15 rather than letting it 'fade out' over a longer period?
The 'hard stop' is mandated by medical device regulatory bodies like the USA's FDA and UK MHRA. Because diabetics make important medical decisions based on the numbers CGMs produce, the devices must operate under a zero-tolerance policy for accuracy (albeit within tight margins compared to a blood fingerstick test, which remains the gold standard for at home testing). CGM manufacturers must mathematically prove to regulators that the sensor maintains an acceptable Mean Absolute Relative Difference during its entire lifespan. Because accuracy plunges steeply after the two-week mark, regulators force an automated kill-switch to keep users safe.
The above does not apply to the Eversense CGM which I understand uses a type of glucose sensor technology different from conventional CGMs.
Data suggests that it can cost between £15 million to £80 million to bring a new CGM to market. That contrasts with £730 million to £2 billion to make a new drug available to the public.
Pharmaceutical and Medical Tech companies are businesses answerable to their stakeholders (shareholders, banks, other creditors) who expect a return on their investment, money loaned to the business to be repaid, raw materials costs to be paid for, etc.
