The antidiabetic drug metformin has been shown to inhibit neoplastic growth by multiple mechanisms,27 one of them being complex I inhibition.28 In addition, it was shown that metformin acts as non-competitive inhibitor of mitochondrial glycerol-3-phosphate dehydrogenase (G3pdh), explaining its antidiabetic properties.29 Using the reported inhibition concentrations of metformin of 0.5 mM for complex I28 and 0.055 mM for G3pdh,29 we simulated the effect of metformin on HCC and healthy liver. The gene discussed is GPD2; the disease is hepatocellular carcinoma.