血管內皮失能是造成糖尿病患在微血管病變的主要因素之一，嚴重的話有可能導致糖尿病患下肢潰瘍甚至是截肢。近紅外光譜儀屬於一種非侵入性的血液動力學監測系統，其優點在於可以讓受測者在動態活動下即時監控帶氧及去氧血紅素之濃度變化。相關的研究文獻證實經由探討血液動力學的訊號內頻率組成成分的改變，可以一窺相關疾病的致病機制。本研究目的在於評估血管調控功能在不同血糖族群的影響下有何變化，期望能為有微血管病變風險的糖尿病患提供更多相關資訊，減少不可挽回傷害的造成。實驗受測者將分為糖尿病、糖尿病前期與正常血糖組，且分別從休息狀態下記錄20分鐘內大腦前額區與小腿腓腸肌的血氧變化及透過重複的等長膝關節伸展運動下量測大腿股外側肌的血氧變化。藉由頻譜分析（Welch’s method）歸納出三個主要的低頻段，其中包含：內皮細胞相關的血管調控（0.005-0.02 Hz）、交感神經支配下的血管調控（0.02-0.06 Hz）與血管平滑肌內的肌源性反應（0.06-0.15 Hz）。研究結果顯示在休息狀態下，糖尿病患下肢肌肉組織有較明顯的內皮細胞活化及交感神經支配活動。此可能顯示糖尿病患有較差的肌肉氧合表現，需透過代償性的血管調控維持肌肉組織間氧氣的傳遞與利用。同時，研究發現罹病初期似乎不影響休息狀態下肌肉血管組織調控。另一方面，研究中也得知肌肉收縮之刺激伴隨著血管調控功能的活化與提高，經過重複的等長肌肉收縮後，糖尿病與糖尿病前期組在內皮細胞活化與交感神經血管調控活動較正常組不明顯。以上結果顯示，無論罹病或罹病初期，其內皮細胞與交感神經的調控已受疾病影響。

Endothelial dysfunction is one of the major factors leading to the impaired microcirculation in diabetics. Near-infrared spectroscopy (NIRS) has been developed as non-invasive method to monitor the concentration change of hemoglobin species. Previous researches have shown that changes in spectral components of NIRS signal might provide some insights into pathogenic mechanisms of diseases. The purpose of present study was to quantify the vascular regulatory mechanisms in diabetes, pre-diabetes and normal groups. NIRS signals were obtained simultaneously from prefrontal cortex and gastrocnemius muscle for 20 min resting measurement, and vastus lateralis muscle for repeatedly isometric knee-extension measurement, respectively. Three dominant frequencies of low-frequency oscillations (LFOs) in NIRS signals including endothelial activity (0.005-0.02 Hz), sympathetic innervation (0.02-0.06 Hz) and myogenic response (0.06-0.15 Hz) have been obtained from the Welch’s method. Our results suggested that the enhanced activity of endothelium and sympathetic nerve aimed to compensate adequate oxygen for the peripheral muscle tissue hypoxia in diabetes during resting. At the same time, initial stage of diabetes might not affect the muscle vascular regulation during resting. In addition, we showed that exercise could enhance the vascular regulatory mechanisms. After repeatedly isometric muscle contraction, the activation of endothelial and sympathetic nerve activity was suppressed in diabetes and pre-diabetes groups. These results may suggest that diabetes could affect the regulation of endothelium and sympathetic nerve even in patients with pre-diabetes.

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