Diabetes mellitus Quiz: Ace Your Exams

A 60-year old male comes to the clinic complaining of numbness in his toes. He cannot quite pinpoint exactly when it started, but for at least the past 3 months the patient has been unable to feel his big toes in his shoes. The patient is able to walk without any weakness in the legs, and he does not have any symptoms in the arms or fingers. The patient’s diet consists mostly of processed food and contains very few raw fruits or vegetables. Medical history includes obesity, chronic lower back pain, and type 2 diabetes. Medications include tylenol and metformin. The patient’s temperature is 37.0°C (98.6°F), pulse is 80/min, respirations are 20/min, and blood pressure is 135/85 mmHg. Physical examination reveals the patient to be comfortable, and the extremity exam demonstrates bilaterally diminished ankle reflexes and loss of monofilament sensation over the forefront of both plantar surfaces. Laboratory studies show a normal complete blood count and a hemoblogin A1c of 10.5%. Which of the following mechanisms is most likely contributing to this patient’s symptoms?