Hepatitis E is mostly autochthonous in Western developed countries, eating pig-derived products being the most frequently documented source. Hepatitis E virus (HEV) infection is usually asymptomatic or self-limiting, but it can cause acute liver failure. HEV serological testing was performed using EUROIMMUN immunoenzymatic assays. HEV RNA in the serum was determined using an in-house real-time reverse transcriptase PCR procedure. The HEV genotype was determined through phylogenetic analysis after Sanger sequencing was performed using an in-house procedure. The case patient, an immunocompetent patient in his 60s with type 2 diabetes and no documented chronic liver disease, was hospitalized in February 2021 in an intensive care unit due to an initially unexplained coma. He presented metformin overdose and fulminant hepatitis E (HEV RNA in the serum was 4,140,000 copies/mL) that evolved toward death. The HEV genotype was 3f. We identified eight previous hepatitis E in diabetic patients, but with no metformin excessive plasma concentration, in the literature. Three patients were liver transplant recipients and three died. HEV infection can be severe and life-threatening in diabetic patients, which warrants HEV testing in this special population in the case of an altered general condition and/or liver cytolysis.