Optical coherence tomography for blood glucose monitoringin vitrothrough spatial and temporal approaches

Abstract

As diabetes causes millions of deaths worldwide every year, new methods for blood glucose monitoring are in demand. Noninvasive approaches may increase patient adherence to treatment while reducing costs, and optical coherence tomography (OCT) may be a feasible alternative to current invasive diagnostics. This study presents two methods for blood sugar monitoring with OCT in vitro. The first, based on spatial statistics, exploits changes in the light total attenuation coefficient caused by different concentrations of glucose in the sample using a 930-nm commercial OCT system. The second, based on temporal analysis, calculates differences in the decorrelation time of the speckle pattern in the OCT signal due to blood viscosity variations with the addition of glucose with data acquired by a custom built Swept Source 1325-nm OCT system. Samples consisted of heparinized mouse blood, phosphate buffer saline, and glucose. Additionally, further samples were prepared by diluting mouse blood with isotonic saline solution to verify the effect of higher multiple scattering components on the ability of the methods to differentiate glucose levels. Our results suggest a direct relationship between glucose concentration and both decorrelation rate and attenuation coefficient, with our systems being able to detect changes of 65 mg/dL in glucose concentration.

Noninvasive Electromagnetic Wave Sensing of Glucose

“…Pretto and co-workers presented a method based on both spatial information on light’s total attenuation coefficient and a temporal analysis of the speckle decorrelation time to predict glucose level [113]. The former is due to a refractive index mismatch and the latter is because of a viscosity change caused by glucose fluctuation.…”

Review of Non-Invasive Glucose Sensing Techniques: Optical, Electrical and Breath Acetone

“…Furthermore, the average size and size distribution of RBCs are different between each individual. Consequently, it is difficult to predict the glucose concentration with accuracy without a RBC reference size [136][137][138].…”

Accurate viscosity measurements of flowing aqueous glucose solutions with suspended scatterers using a dynamic light scattering approach with optical coherence tomography

“…We then compare our estimates with the reported values of uðxÞ ¼ AE0.8 mM 9 and uðxÞ ¼ AE5 mM. 28 Our uncertainty for the spectral width measurements no-flow conditions is 30 mHz (see Table 1); we assume the same for the case of measuring the power spectrum from blood under noflow conditions. † In Ref.…”

“…In Ref. 28 (mouse blood diluted with phosphate buffered saline), the correlation time at x ¼ 20 mM is 7.1 ms ( Fig . This estimated ∼250× improvement in uðxÞ for (diluted) mouse blood is also very encouraging.…”

“…[20][21][22][23] Currently, two OCTbased approaches are explored for noninvasive glucometry in blood, based on signal attenuation [24][25][26] and correlation function analyses. 9,27,28 However, accuracy, robustness, and sensitivity/ specificity are currently insufficient for clinical implementations, for example, in diabetic patients use. Specifically, attenuation techniques are complicated due to the attenuation as a function of glucose concentration having considerable fluctuations; 29 therefore, this approach does not appear promising for use in clinical practice.…”