A diabetic individual gradually becomes more prone to infections and can be prescribed Metformin concurrently with a broad spectrum antibiotic like Cefepime. Our research examines the possibility of drug-drug interaction between Metformin and Cefepime in a number of in vitro and in vivo parameters. The in vitro tests including Differential Scanning Calorimeter, Scanning Electron Microscope and Fourier Transform Infra Red analysis were found to reveal visible changes in melting points, morphological structures and rearrangement of functional groups due to the interaction. The disc diffusion method was used to compare the antimicrobial properties of all the test samples and the antimicrobial potential of Cefepime was found to be suppressed moderately after in vitro interaction with Metformin. The alteration of the in vivo antidiabetic activity of Metformin was evaluated in streptozotocin-induced Long-Evans Rats, and the anti-hyperglycemic effect of Metformin was detected to decrease significantly in the resulting product of this interaction.