A smartwatch claiming to offer "non-invasive blood glucose monitoring" not only measures people but also gives a towel a "blood glucose reading" of 4.9 mmol/L. Behind this absurd scene lies a health trap faced by countless diabetes patients. "Doctor, my newly purchased watch can measure blood glucose non-invasively. Does this mean I no longer need to prick my finger?" In the clinic, I encounter patients asking this question with hopeful anticipation almost every week. Seeing the dense needle marks on their fingers, I fully understand this longing. But as a doctor, I must provide the most cautious answer: Currently, no smartwatch on the market claiming to offer "non-invasive blood glucose monitoring" has achieved medical-grade accuracy. Such devices must not be used for diabetes diagnosis or treatment decisions. Market Chaos Health anxiety is fueling a chaotic market. On e-commerce platforms, numerous smartwatches labeled as "non-invasive blood glucose monitors" are priced from a few hundred to several thousand yuan, with some best-selling models reaching sales volumes as high as millions. However, an investigation by CCTV.com revealed a shocking truth: these watches can even assign a "blood glucose value" of 4.9 mmol/L to a dry towel. In practical comparisons, their readings may deviate from those of standard blood glucose meters by as much as 2-6 mmol/L, with no discernible pattern. "The error ranges from 2 to 6 mmol/L, almost completely random," lamented a consumer who purchased such a watch to monitor their mother's blood glucose. Such inaccuracy is medically dangerous. Clinicians point out that the acceptable range for blood glucose monitoring is very narrow. Errors of this magnitude are "equivalent to not measuring at all, or even worse than not measuring," because they can lead patients to make completely opposite decisions—failing to administer additional insulin when needed due to falsely normal readings, or not promptly consuming carbohydrates when at risk of hypoglycemia. Technical Barriers Why is achieving non-invasive blood glucose monitoring so difficult? Because it is hailed as the "Mount Everest" of biosensing. True blood glucose refers to the concentration of glucose in the bloodstream. The most direct and accurate method must involve testing the blood itself. Currently, the vast majority of "non-invasive blood glucose watches" on the market operate by attempting to estimate blood glucose levels indirectly through monitoring physiological indicators such as heart rate and blood pressure. However, Dr. Xie Yuting from Xiangya Second Hospital of Central South University clearly states that the correlation between these indicators and blood glucose concentration is too weak. They are highly susceptible to interference from factors like exercise, emotions, and environment, making them utterly unreliable for reflecting true blood glucose levels. Some products use optical sensors, but skin thickness, temperature, humidity, and other factors can significantly interfere with the measurements. This is why, to date, no smartwatch or fitness tracker has received approval from China's National Medical Products Administration (NMPA) or the U.S. FDA for medical-purpose non-invasive blood glucose monitoring. Glimmer of Hope So, is non-invasive blood glucose monitoring an unattainable fantasy? Not exactly. Genuine scientific research is steadily progressing, but the path may differ from the "watch" we imagine. In February 2025, a team led by Professor Wang Weiqing from Ruijin Hospital, affiliated with Shanghai Jiao Tong University School of Medicine, achieved a significant breakthrough. They developed a "multi-micro spatial offset Raman scattering (mμSORS)" technology that allows non-invasive blood glucose measurement simply by placing the palm against the device. This technology performed well in a clinical study involving 230 participants, showing an average absolute error of 14.6% compared to the venous blood "gold standard." But does this mean it can replace fingertip blood sampling? Not yet. First, this is a device for hospital use, not a wearable watch. Second, a 14.6% error is still too high for patients requiring precise insulin dosage adjustments. For comparison, current top-tier minimally invasive continuous glucose monitoring (CGM) systems can control errors to below 9%. The significance of this research lies in demonstrating the feasibility of non-invasive detection and pointing the way for future technological development—directly detecting specific optical signals related to blood glucose in skin interstitial fluid, rather than indirect estimation. Translating this into a reliable, compact, and home-use product will require more time. Rational Choices Faced with a dazzling array of products and enticing advertisements, how should diabetes patients make their choice? Please remember the following principles, which are core to ensuring your safety. First, recognize the wordplay between "monitoring" and "testing." Many product pages prominently display "blood glucose monitoring" in large font but note in small print in a corner "not for diagnostic or treatment purposes." "Monitoring" merely indicates showing trends, while "testing" refers to use for medical evaluation. This is entirely a tactic by merchants to circumvent regulation. Second, check for official certification. Before purchasing any device for health management, be sure to verify whether it has obtained a Medical Device Registration Certificate issued by the National Medical Products Administration (NMPA). This is the most basic guarantee of a product's safety and effectiveness. Third, understand current reliable blood glucose monitoring methods: Fingertip Blood Glucose Meter: Immediate and reliable, it is the "gold standard" for self-blood glucose management. Ensure proper operation. Continuous Glucose Monitoring (CGM) System: This is currently the most technologically advanced and information-comprehensive monitoring method. It uses a tiny sensor inserted under the skin to measure interstitial fluid glucose concentration every few minutes, providing a complete picture of daily blood glucose fluctuations and detecting hidden highs and lows. The latest iCGM (integrated CGM) standard represents the highest international accuracy requirements. For patients requiring insulin therapy, especially those with type 1 diabetes or significant blood glucose fluctuations, CGM can greatly enhance treatment safety and quality of life. It is widely recommended by authoritative guidelines both domestically and internationally. A smartwatch is performing a "blood glucose test" on a brown towel, with a blood glucose value prominently displayed on the screen. This image is full of irony, yet it accurately portrays the current market. Genuine medical progress, like the non-invasive detection research at Ruijin Hospital, is steadily advancing in rigorous laboratories and clinical trials. Meanwhile, those exaggerated "black technology" products on the market not only drain patients' wallets but may also provide fatal misinformation at the most critical moments. When it comes to health, sometimes the simplest, proven methods are the most reliable. Until non-invasive blood glucose monitoring technology truly matures and gains approval, trust science, follow medical advice, and do not gamble your health on those华丽的谎言.