Diabetic Sensory and Motor Neuropathy

A 65-year-old woman with a 5-year history of type 2 diabetes (a recent hemoglobin A(1C) level was 9.5%) reports the recent onset of burning, tingling, and stabbing pain in her feet that is worse at night and interferes with sleep and activities of daily living. Her medications include 500 mg of metformin and 2 mg of glimepiride, each taken twice daily. On physical examination, the patient is alert and oriented to person, place, and time. Her blood pressure is 140/90 mm Hg. She has reduced sensation to pinpricks in the knees, reduced ability to detect vibration from a 128-Hz tuning fork, and a loss of proprioception and of sensation to a 1-g monofilament (but not to a 10-g monofilament) in her toes. Strength in the lower legs is 5 out of 5 (normal) proximally and 4 out of 5 distally, and there is slightly weak dorsiflexion of both big toes, with no indication of entrapment. Her ankle reflexes are absent. She has no foot ulcers, and her pulses are easily palpable. How should her case be further evaluated and managed?