Glucose in drinks is one of the key factors in the management and prevention of diabetes. Although several systems have been developed to monitor blood glucose levels as an indicator of diabetes, information on the actual intake of nutrients and their amounts is more effective for improving dietary habits. In this study, to evaluate the actual amount of glucose intake, we proposed a mouthguard-type sensor with an enzymatic biosensor for the direct measurement of the glucose concentration of ingested drinks. The fabricated biosensor was capable of quantifying glucose concentrations in the range of 1 μM–1 mM and showed measurement results equivalent to those of glucose measurement kits for some commercial drinks. The mouthguard-type sensor also showed quantification characteristics equivalent to the biosensor in wired measurements. In addition, wireless measurements with a mouthguard-type sensor were also demonstrated using a Bluetooth Low Energy potentiostat. These results suggest the potential application of real-time glucose intake measurement with the proposed mouthguard-type sensor.