Glucose sensing through the use of radio waves is indirect, relying on predictable alterations in how ionic solutes like sodium respond to alternating electromagnetic fields in the presence of glucose. The normal interference in specific radio frequencies caused by sodium are impeded by surrounding glucose molecules. Glucose is not directly affected by longer wavelength radio and microwave frequencies, so it's presence cannot be directly measured. But because it is the major solute in a size range close to that of sodium, it generates much of the interference that is seen in sodium's normal impedance pattern.
Glucose could theoretically be measured through this interference pattern. Glucose's impedance of sodium varies at different frequencies. By using 3 or 4 precisely selected frequencies, it is hoped that glucose can be accurately measured with little risk of user error.
Are there advantages?
The big advantages of radio sensors are that they are painless, require no blood and take just a few seconds to complete. Compared to IR waves, radio waves undergo much less interference and pass readily through the human body, giving much higher transmission rates.
Off-the-shelf equipment could be used in innovative ways to keep costs low. Radiowave frequencies are absorbed by charged elements and proteins in the plasma and extracellular fluid. If glucose modulates these absorption patterns, careful selection of radio frequencies might allow glucose, as well as other molecules like cholesterol and glycosylated proteins, to be measured non-invasively. Very quick measurement times would also be a major advantage.
However, this technology is still in development. No major firms have directed any substantial financial resources into this research area to our awareness.