Patient with Diabetes

An 88-year-old man who reported he did not smoke and who had a long-standing history of diabetes mellitus, hypertension, and hypercholesterolemia was admitted to the hospital with a 4-month history of pain in the right lower leg.

The ankle–brachial index was 0.2 in the right leg and 0.8 in the left leg. The history and physical examination were otherwise unremarkable, with no evidence of a vasculitic, hypercoagulable, or embolic disorder.

What’s the diagnosis ?