As the vane of high-tech smart products, Apple has entered the field of health wear a few years ago, and there are rumors that Apple's smartwatch will launch a blood sugar monitoring function. However, from the S4 to the latest S8, we have not waited for the release of the blood sugar monitoring function, which made many netizens feel that they have been "fudged" by the "toothpaste squeeze" press conference again.
In addition to Apple, many technology giants such as Samsung have invested heavily in non-invasive blood glucose monitoring research. Samsung's next-generation Galaxy Watch will support blood sugar monitoring without piercing the skin, and was expected to roll out the feature in the Galaxy Watch 4, but the Galaxy Watch 4 was not released. So it is conceivable that the blood sugar monitoring function is really stumped by various technology giants.
Why is blood sugar monitoring so difficult?
Blood sugar monitoring is not difficult, but it is difficult to achieve non-invasive. The research on "non-invasive measurement of glucose" has been going on for decades, but so far, no reliable technology has been commercialized.
Various sensors such as glucose biosensors, information transmitters, and information receivers are integrated on wearable devices. In addition to external factors such as wearing, operation, temperature and humidity, it is difficult to achieve accuracy.
For example, glucose biosensors commonly used in CGM (continuous glucose monitoring) monitoring can measure the glucose content of the human body in body fluids such as sweat, saliva, urine, and tears. Most use optical technology, infrared technology. This link is critical to the accuracy of the resulting data, but factors such as noise heat, calibration offset, low signal-to-noise ratio, and environmental sensitivity all affect the accuracy of the data.
Principle of non-invasive blood glucose monitoring
At present, the method of non-invasive blood glucose monitoring mainly uses the combination of blood glucose-related indices and sensors, and uses algorithms to calculate the corresponding blood glucose value. Before understanding the principle of non-invasive blood glucose monitoring, you need to understand the blood sugar.
Main sources of blood sugar:
Food digestion and absorption;
The breakdown of glycogen stored in the liver;
Conversion of fat and protein.
The destination of blood sugar conversion:
Oxidation into energy;
Converted to glycogen and stored in the liver, kidneys and muscles;
Converted to other nutrients such as fat and protein for storage.
Pancreatic islets are the main organs in the body that regulate blood sugar levels in the body, and the liver stores glycogen. Blood sugar concentration is also regulated by nerve and endocrine hormones.
At the "Smart Wearable Sub-Forum" in 2022, it was shared that the human characteristics currently available in non-invasive blood glucose monitoring are:
Breathing Gas - Acetone : The concentration of acetone in human breath is associated with many diseases, such as asthma, lung cancer and diabetes. Many researchers have done related research, and there is a certain correlation between the glucose molecules in acetone and the glucose molecules in the body.
Metabolic heat: A non-invasive blood glucose meter based on the principle of metabolic heat, obtains data such as heat generated by human metabolism, blood flow rate, etc. through temperature sensors, infrared sensors, optical measurement and other devices, and then calculates the value of blood sugar concentration. The core idea of metabolic heat is that the heat of the human body is balanced, that is to say, the heat generated and the heat dissipated are balanced. If the heat dissipated and the factors that generate heat are known, the blood sugar of glucose can be calculated. There are already related products on the market.
Saliva, Eyes, Urine: A saliva-based approach is a non-invasive blood glucose monitoring. In the paper of some researchers, the blood sugar sensor is integrated on the braces to detect the concentration of blood sugar, which actually detects glucose oxidase.
ECG Signals: There is a correlation between human physiological signals such as ECG changes and blood sugar levels. By adopting the segmental ECG heartbeat waveform, a DBSCAN-CNN-based algorithm is designed to monitor blood glucose levels
It can be seen that there are many difficulties to be overcome to achieve non-invasiveness:
Blood sugar has no color in the visible light band and is not easy to distinguish;
The distribution of sugar in the body is not concentrated in the blood vessels, and the glucose content in each tissue is different, in addition, the blood sugar concentration will also change with the state of the body;
The concentration of glucose in the blood is very low, and the blood sugar level can be reduced to half of the normal value;
Blood sugar is chemically similar to many other compounds in the body, and some compounds in the blood, such as albumin, also bind to blood sugar, interfering with measured values.
Ofcourse, from invasive to non-invasive, this is actually a process of gradually moving away from blood, which means that the technology is becoming more and more complex. Compared with traditional invasive blood glucose meters, there is still a long way to go to make medical-grade non-invasive blood glucose monitoring equipment with accurate results. In the field of health wear, the non-invasive blood glucose monitoring market is huge and the demand is strong. Whoever can stand out from it will be able to seize the market opportunity, and it will also bring great convenience to those who need blood sugar monitoring.