The present work aims at studying the in vitro anti-diabetic activity of T. bellirica embedded gold nanoparticles synthesized using T. bellirica dried fruit and seed extract by alpha-amylase assay. Gold nanoparticles were prepared from various green synthesis routes with T. bellirica aqueous extracts. The products are well characterized by Ultraviolet–Visible spectroscopy (UV–Vis), Field Emission Scanning Electron Microscopy (FESEM), Fourier-Transform Infrared spectroscopy (FTIR) and Transmission Electron Microscopy (TEM). Gold nanoparticles of violet–pink colour were synthesized by five different methods. Optimization of reaction conditions was also carried out. The biosynthesized gold nanoparticles (TBNg 150 µl) showed good inhibition efficiency (46 and 42%) against Aspergillus oryzae and Porcine pancreas, respectively, compared to the standard acarbose (60.71 and 61.90%, respectively). Microwave-assisted synthesis gave T. bellirica mediated gold nanoparticles with less time (3:00 and 3:80 s) for the ratio of plant extract and gold solution 5:1 and 3:1, respectively. The UV–Visible absorption spectral analysis of synthesized nano exhibited Surface Plasmon Resonance at 560 nm range indicating the formation of gold nanoparticles. TEM results revealed various shapes of nanogold namely spherical, hexagonal and triangular shaped gold nanoparticles. The smallest size of nanoparticle synthesized was 5.1 nm. The results also evidence, alpha-amylase assay as a facile screening tool for assessing the anti-diabetic activity of plant extracts.