What is the appropriate evaluation and treatment for a 58‑year‑old man with diabetes who reports tingling and numbness in his feet?

Evaluation and Treatment of Diabetic Peripheral Neuropathy

Immediate Clinical Assessment

Start pregabalin, duloxetine, or gabapentin immediately for neuropathic pain while simultaneously optimizing glycemic control and ruling out other reversible causes of neuropathy. 1, 2

Confirm the Diagnosis

• Perform focused neurologic examination testing small fiber function (pinprick sensation and temperature perception) and large fiber function (vibration with 128-Hz tuning fork and ankle reflexes) to confirm distal sensorimotor polyneuropathy 1, 2
• Document characteristic symptoms: burning pain, electric shock-like sensations, tingling, numbness in stocking distribution, or contact pain from bedsheets (allodynia) that typically worsens at night 1
• Perform 10-g monofilament testing at multiple foot sites to assess for loss of protective sensation, which predicts ulceration risk 1, 2

Rule Out Other Causes (Diabetic Neuropathy is a Diagnosis of Exclusion)

• Measure vitamin B12 with metabolites (methylmalonic acid and homocysteine), especially critical since he likely takes metformin which depletes B12 3, 2
• Check thyroid-stimulating hormone (TSH) to exclude hypothyroidism 3, 2
• Order serum protein electrophoresis with immunofixation to detect monoclonal gammopathies, an underrecognized cause 3
• Obtain complete metabolic panel to assess renal function and electrolytes 3

First-Line Pharmacologic Management

Choose one of three evidence-based agents based on his specific comorbidities: 1, 3, 2

• Duloxetine 60 mg daily is preferred if he has comorbid depression; provides 30-50% pain reduction and may improve numbness/tingling 1, 3
• Gabapentin titrated to 1200 mg daily (divided three times daily) achieves at least 50% pain reduction in 38% of patients and is the most cost-effective option 1, 3
• Pregabalin 150-300 mg daily (divided twice daily) is FDA-approved specifically for diabetic neuropathic pain 1, 4

Assess medication response objectively at 2-4 weeks since adverse effects are common and serious complications can occur; if inadequate response, switch to a different first-line agent rather than adding medications 3, 2

Second-Line Options if First-Line Fails

• Consider tricyclic antidepressants (amitriptyline 25-75 mg at bedtime), though use caution given his age due to anticholinergic effects (urinary retention, confusion, falls) 3, 5
• Venlafaxine is an alternative SNRI if duloxetine is not tolerated 3
• Reserve tramadol or opioids only for refractory cases; generally avoid due to addiction risk and lack of long-term efficacy data 1, 4

Disease-Modifying Interventions

Optimize Glycemic Control Gradually

• Target individualized HbA1c based on his age, comorbidities, and hypoglycemia risk; tight control prevents neuropathy in type 1 diabetes and modestly slows progression in type 2 diabetes 1, 2
• Do not rapidly lower HbA1c if severely elevated (>10%), as this paradoxically worsens neuropathic symptoms through "treatment-induced neuropathy" 2

Address Cardiovascular Risk Factors

• Control blood pressure and manage lipids aggressively, as these contribute significantly to neuropathy progression in type 2 diabetes 1, 2

Correct Vitamin B12 Deficiency if Present

• Supplement with 2500 mcg daily if deficiency is confirmed 3

Critical Preventive Foot Care (Prevent Ulceration and Amputation)

• Educate him on daily foot inspection for cuts, blisters, pressure areas, or color changes 1, 2
• Recommend protective footwear with adequate cushioning and proper fit; avoid walking barefoot 3, 2
• Arrange podiatry referral for regular foot care given his sensory loss 3, 2
• Emphasize immediate reporting of any foot wounds, as mortality is 23% at 2 years after foot ulceration 6
• Perform annual 10-g monofilament testing to monitor progression of sensory loss 1, 3, 2

Common Pitfalls to Avoid

• Do not prescribe nitrofurantoin for urinary tract infections in diabetic patients, as it significantly increases neuropathy risk 2
• Do not delay treatment waiting for electrodiagnostic studies; clinical diagnosis is sufficient to initiate therapy 2
• Do not overlook autonomic neuropathy symptoms at each visit: orthostatic dizziness, gastroparesis (erratic glucose control, early satiety), erectile dysfunction, or bladder dysfunction 1, 2

Monitoring and Follow-Up

• Perform annual comprehensive neuropathy assessment including sensory testing and foot examination going forward 3, 2
• Monitor for progression to loss of protective sensation, which dramatically increases ulceration risk 1, 2