Joe Smith is 66 years old and presents with a one-year history of increasing burning, tingling, and electric shock–like pain in his feet. He says that the symptoms were initially mild, but have become progressively bothersome over the past 7 weeks. He notes that the symptoms are worse at night. He has no past history of similar symptoms.

During your examination, Mr. Smith rates his average daily discomfort as a 6 on a 0 to 10 scale. He denies any numbness, weakness, difficulty walking, or similar symptoms elsewhere in his body. He also denies headache, speech difficulties, loss of balance, tremor, or any memory loss or confusion.

He does not smoke. He drinks 3 beers a week and unloads trucks for a delivery service, where he has worked for 10 years. He denies any occupational/environmental exposures. His family history is remarkable for diabetes in his 69-year-old sister and a “thyroid problem” and bleeding ulcer (requiring emergency surgery) in his 86-year-old mother. He has not seen a physician in the past 10 years because he had no health insurance, but recently signed up for coverage through the Affordable Care Act.

His vital signs are as follows: blood pressure 134/79 mm Hg, heart rate 82 beats per minute (bpm), and respiratory rate 16 breaths per minute. He weighs 190 pounds, with a body mass index (BMI) of 29 kg/m².

Notable findings on the physical exam include:

• irregular caliber of the retinal veins (ie, venous beading, consisting of alternating areas of venous dilation and constriction) on funduscopic exam¹
• early diastolic sound at the apex of the heart in the left lateral decubitus position
• 10-g monofilament testing that was normal and symmetrical.

The rest of his physical exam is unremarkable. You are concerned that this patient not only might have diabetes, but also might have diabetic peripheral neuropathy (DPN).