Type 2 diabetes is an increasingly prevalent disease, with more than 400 million people worldwide diagnosed in 2016. As a stable and accurate biomarker, glycated hemoglobin (HbA1c) is clinically used to diagnose type 2 diabetes with a threshold of 6.5% HbA1c among total hemoglobin (Hb). Current methods such as boronate affinity chromatography or enzymatic assay involve complex processing of large-volume blood samples, which inhibits real-time measurement in clinic. Moreover, these methods cannot measure the HbA1c fraction at single red blood cell level, thus unable to separate the contribution by diabetes from other factors such as diseases related to lifetime of red blood cells. Here, we demonstrate a transient absorption imaging approach that is able to differentiate HbA1c from Hb based on the excited state dynamics measurement. HbA1c fraction inside a single red blood cell is derived quantitatively through phasor analysis. HbA1c fraction distribution for diabetic blood is found apparently different from that for healthy blood. A mathematical model is developed to derive the long-term glucose concentration in the blood. Our technology provides a new way to study heme modification and to derive clinically important information avoid of glucose fluctuation in the bloodstream.
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