A Patient With Diabetes and Spontaneous Blistering of the Right Lower Extremity

A 42-year-old man with hypertension, type 2 diabetes diagnosed at age 25 years, and gastroparesis presented to the emergency department with right lower extremity blisters that had developed spontaneously over the prior 36 hours. He reported a tingling sensation in the affected area but no pruritus or pain. He had no history of leg trauma and no chemical or extreme temperature exposure. Medications included insulin lispro (sliding scale 3 times daily) and insulin glargine (20 units nightly). On physical examination, he was afebrile and had normal vital signs. His extremities were warm with palpable distal pulses. Hyperpigmented macules were present on the anterior lower legs below the knees, and tense bullae were present on the anterior aspect of the right lower extremity, dorsal foot surface, and toes (Figure). There was no surrounding erythema or edema, and findings on the remainder of the skin and mucocutaneous examination were unremarkable. Laboratory testing revealed a blood glucose level of 375 mg/dL (20.81 mmol/L) and hemoglobin A_1c level of 9.8%. Results of a basic metabolic panel and complete blood cell count were within reference range except for mild anemia (hemoglobin level, 10.9 g/dL).