Atezolizumab is a humanised monoclonal IgG1 antibody that is used in treating many solid malignancies. Endocrinopathies are known but a rare adverse event of these immunotherapeutic drugs. Autoimmune diabetes induced by atezolizumab has been rarely reported in the literature. We report the case of a woman in her eighth decade with no known history of diabetes who developed new-onset autoimmune diabetes and Takotsubo cardiomyopathy due to the adverse effects of atezolizumab therapy for hepatocellular carcinoma. We also review the characteristics and outcomes of cases previously reported in the literature.