Bullous eruption of diabetes is a cutaneous sign of diabetes mellitus. Patients with this disorder manifest a sudden onset of intraepidermal or subepidermal bullae, which are primarily confined to the extremities and heal within several weeks without scarring. Our patient had severe diabetes and experienced two episodes of bullae associated with intense, ultraviolet light exposure. Negative immunofluorescence, early disappearance of anchoring filaments and half-desmosomes between cell membrane and basal lamina, and the absence of urinary uroporphyrins separate this entity from certain similar-appearing conditions. Cation imbalance, precipitated by renal failure, could be a possible causal factor.