Abstract

Diabetic neuropathy may be a result of disturbed vasomotion, the spontaneous rhythmic oscillations of vessel diameter, flow, or pressure in the microcirculation. To examine the differences in vasomotion prior to overt diabetes and with diagnosed diabetes, metabolic and blood flow measurements were obtained from three metabolically distinct groups of nonhuman primates: normoglycemic, metabolic syndrome/prediabetic, and overtly diabetic. Three of these indices characterize spectral properties of microcirculatory vasomotion: (1) the fraction of spectral power in a band around 2.0 Hz, (2) the ratio of spectral power in a band around 1.0 Hz to that around 2.0 Hz, (3) the Hurst exponent. The rest were more traditional measures including (4) fasting plasma Glucose (FPG), (5) glycosylated hemoglobin level (HbA1c), (6) fasting insulin levels (IRI), (7) average systolic blood pressure, and (8) average diastolic blood pressure. We found that the mean fraction of the spectral power of the vasomotion in the 2 Hz band is significantly greater in the nondiabetic than in the diabetic group. Similarly, the ratio of the spectral power in the 1.0 Hz band to that in the 2.0 Hz band was significantly higher among the diabetic subjects than in the nondiabetic and prediabetic subjects. Principal component analysis (PCA) of the ensemble of eight measures revealed that values of the first principal component in the diabetic group were highly and significantly different from those of the normal and prediabetic groups, which are also significantly different from each other. Furthermore, the spectral measures of vasomotion offered a distinct advantage over the traditional physiological variables in distinguishing the normal subjects from the prediabetic group, and are likely to reflect very early autonomic dysfunction.

Keywords: Diabetes, Vasomotion, Spectral analysis, Principal component analysis

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