Abstract Body: Hydrogen sulfide (H₂S) generated in the endothelium of small arteries has been shown to contribute to vasodilation, angiogenesis, and antioxidant properties. We have developed a non-invasive way to measure H₂S emitted by the skin (TAGS™) and have shown that the ratio of leg:arm emitted levels correlate with severity of microvascular impairment in subjects with diabetes. This study evaluated the correlation of transdermal H₂S ratios with the current gold standard method of evaluating leg skin blood flow, transcutaneous oxygen pressures (tcpO₂). TAGS™ measurements were made on the forearm and lower limbs in subjects to calculate the leg:arm ratio while tcpO₂ was recorded only from legs. Other measurements included ankle brachial index (ABI), fasting blood glucose, HbA1c, plasma lipids, blood pressure, and BMI. We observed that TAGS™ ratios correlated strongly with HbA1c (p = 0.0002) and with tcpO₂ (p = 0.0009). In addition, TAGS ratios were significantly lower in subjects with diabetes (0.69 +/- 0.18) compared to healthy controls (1.13 +/- 0.40) (p = <0.0001). These results suggest lower leg:arm ratios of transdermal H₂S measurements are indicative of impaired microvascular function and that the TAGS™ measurements may be a simpler way than tcpO₂ to detect and monitor diminished skin blood flow that leads to PAD complications.