Background: Sweat contains glucose that can accurately reflect blood glucose. However, skin surface glucose can confound these measurements. Methods: A perfusion method was used to rapidly harvest sweat from forearm sites on human subjects. The sweat samples were analyzed for glucose by high-performance liquid chromatography methods and compared with the results obtained with a blood glucose meter. Results: The results of 23 different studies of seven individual subjects with diabetes show a strong correlation between sweat glucose and blood glucose. Conclusion: Sweat glucose, when properly harvested to prevent contamination from other sources on the skin's surface, can accurately reflect blood glucose levels.