Noninvasive, Rapid, and Ultrasensitive Detection of Salivary Glycated Hemoglobin for Point-of-Care Testing of Diabetes.

The glycated hemoglobin ratio (HbA1c %) serves as the gold standard for diabetes diagnosis, but traditional detection methods require invasive blood testing. Although saliva holds promising noninvasive potential, the complex salivary matrix and the low abundance of salivary hemoglobin (Hb) and glycated hemoglobin (HbA1c) restrict the development of reliable immunoassays. Here, we present an HbA1c/Hb dual-detection lateral flow assay (LFA) platform for rapid and noninvasive quantification of salivary HbA1c %. The assay integrates two distinct capture strategies onto a single LFA strip: a streptavidin (SA)-biotin bridging system for HbA1c (T1 line) and a conventional double-antibody sandwich format for nonglycated Hb (T2 line). Consequently, our platform enables simultaneous and single-step measurement for the absolute concentrations of both Hb and HbA1c, facilitating the precise calculation of the HbA1c %. The analytical accuracy was validated against paired venous blood samples. Additionally, coupling with a low-cost, 3D-printed, and smartphone-based fluorescence reader, the system provides an economical and efficient point-of care testing solution, particularly for clinical preliminary screening and at-home self-testing.