The incidence of diabetes mellitus is rapidly increasing in developed and developing countries. Point-of-care testing (POCT) is a useful tool in developing countries with a poorly developed infrastructure. Glycated hemoglobin (HbA1c) is a reliable indicator for diabetes mellitus testing, and POCT devices for HbA1c have been developed. In this study, we developed a microfluidic channel device for quantifying HbA1c that is small and easy to measure on the basis of the latex aggregation method. Microfluidic channels were integrated into the front and back surfaces of a polymethyl methacrylate substrate of 40 mm width × 60 mm length × 1 mm thickness. The front side was composed of a main channel, including a mixing channel. The reverse side featured a channel for funneling the gas (nitrogen) generated from the light-gas generation pumps. In these pumps, the azide compound was decomposed by light irradiation and nitrogen gas was generated. The generated nitrogen gas enabled liquid transfer. The optical system consisted of an LED (660 nm) and a photodetector. Its sensitivity was improved by optimizing the aperture size. This system can quantify HbA1c, and at HbA1c concentrations of 0, 4.4, 9.6, and 13.9%, the absorbance values were 0, 0.11, 0.28, and 0.39, respectively. A linear relationship between concentration and absorbance was observed with a determination coefficient of 0.99, a standard deviation (SD) of 0.009–0.015, and a coefficient of variation (CV) of 2.4–9.3%. The concentration of HbA1c in whole blood could also be determined on the basis of the calibration curve obtained. This system is expected to be useful for HbA1c testing in remote areas and clinics.