The dielectric properties of 0.9% NaC1 in water with small content of sugar and glucose, as well as of human skin, were measured in the millimeter (MM) waves range. The measurement methods were chosen so that one could use them for the nondestructive control of glucose content (i.e., measurement only reflection of an electromagnetic wave, without penetrating into the medium). To determine ε' and ε", of lossy materials one usually measures the power reflection coefficient and the phase of the reflected wave with the help of sophisticated and expensive network vector analyzers. We developed a sufficiently simple method and scheme, which consists in measuring the minimum of the power reflection coefficient R(f) = R_(min)(f_(min)) and its frequency f_(min) in the cases of corresponding to this minimum from the following structures: a specially chosen plane-parallel matching plate made of a low-loss dielectric or resonator - a medium under measurement with high losses (solution, blood, skin). This method was realized in the MM waves range. Dielectric properties of glucose solutions in water and in a 0.9% NaCl solution (physiological solution) have been measured. Also was measured dielectric properties os human skin. The values of ε' and ε" have been measured near the elbow joint in the frequency range from 30 to 80 GHz. Above 40 GHz, these data have been obtained for the first time, whereas, at frequencies of 30-40 GHz, the values of ε" obtained in our experiments are higher than those available in the literature. Our method allows a real-time noninvasive determination of glucose content in blood by measuring reflection on skin. We established a clear correlation between glucose content W and the measured value of reflection coefficient as W increases after an oral glucose tolerance test (OGTT) on an empty stomach. The functions R_(min)(W) show similar but individual behavior for each test person. It was established a correlation between glucose content Wafter OGTT and the properties of skin. The results of the measurements described can be used to implement real-time, including noninvasive, measurements of small glucose (sugar) content in water, physiological solution, and blood.
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