Glucose Uptake Assay

3T3-L1 adipocytes and C2C12 myotubes were treated with metformin (Sangon Bio-Tech, Shanghai, China) as the positive control, phloretin (BioVision, Milpitas, CA, United States) as the negative control, and NAR for 4 h. Glucose uptake was measured using the 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxy-glucose (2-NBDG) glucose uptake assay kit (BioVision, Milpitas, CA, United States) (Waters et al., 2019). Images were taken by fluorescence microscope (Zeiss, Jena, Germany). The fluorescence intensity of each photograph was measured by Image-Pro Plus software (Media Cybernetics, Rockville, MD, United States). The drug-free group was used as a control. The relative ratio of each group was obtained after normalization.