Some smartwatches are actually making up their readings – which is why I keep telling you people never to buy cheap, unbranded Apple Watch dupes

• Germany's Federal Network Agency investigated suspicious listings of tech products, including smartwatches
• Many of these products are advertising glucose monitoring features
• There is no reliable non-invasive way of monitoring glucose, and some watches were found to simply estimate or make up readings

As well as extensively testing the best smartwatches, we also occasionally test the worst products out there as well. A few years ago, I tried out the cheapest fitness tracker I could find against a Garmin Forerunner 955 Solar, and got predictably dodgy results. After testing a few more of these brandless also-rans, I concluded that generally, they weren't very good.

However, some people are still clearly buying them, as the likes of Amazon and Temu are swarmed with listings like "Advanced GLUOOSE Reading Smartwatch 24/7 Heart Rate Blood Oxygen 1.9'' HD Portable Fitness Activity Tracker for Outdoor Sports".

Unfortunately, any poor recipients of watches like these are going to be swindled, as no smartwatch can accurately measure blood glucose levels – or even 'gluoose' as the listing above spells it – with LEDs alone. Continuous glucose monitors like Abbott's Lingo, which involves an invasive needle attached to a Bluetooth-enabled chip, are the only commercially available smart tech able to accurately do so.

The Federal Network Agency, a German regulatory body, investigated a lot of online listings in 2025 and found serious flaws in 7.7 million different products, and smartwatches were the worst offenders. Spotted via NotebookCheck, these flaws ranged from missing CE markings to listing features like blood glucose monitoring, which were actually "simulated" – as in, the device was not actually reading the user's blood glucose at all, merely looking like it was.

One such smartwatch that made these claims, the Kospet iHeal 6, was actually taken off the market in 2024, but still sold in German territories, after the ruling to remove it was made.

Smartwatches provide information about your health, but not legally protected health information, and as such their features aren't subject to legislation such as HIPAA in the US, or required to be classed as fit for use in a medical setting. Most serious smartwatch manufacturers such as Apple seek US FDA approval for features such as hypertension detection.

If you're just looking to flood the market with cheap smartwatch clones, however, no such stringent legislation need apply. Simply make an app that looks like it's doing what it's actually supposed to be doing, and bang the device on Amazon for $50 / £40 / AU$65 or less.

When I reviewed the cheap Viido fitness tracker against the Garmin watch in the link above, everything was wrong, from its step count and heart rate tracker being wildly swingy, to its app looking like a dodgy piece of malware. These devices aren't reliable and there's no point buying them.

If platforms like Amazon won't halt their sale, it's up to us to be diligent, responsible consumers and do a bit of research before pulling the trigger. Might I direct you to our best cheap smartwatches guide, to start?

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