A 65-year-old Japanese man presented to our hospital in June 2013 with a 6-day history of fever and fatigue, a 24-h history of thirst, and polyuria. His temperature was 37.8 and he was alert. However, laboratory tests revealed severe hyperglycemia, undetectable C-peptide levels, and diabetic ketoacidosis. Serum antibody testing confirmed a Coxsackie virus A2 infection. A variety of viral infections are reported to be involved in the development of fulminant type 1 diabetes mellitus (FT1D). Our patient is the first reported case of FT1D associated with Coxsackie virus A2 infection and supports the etiological role of common viral infections in FT1D.