What is the likely diagnosis and management for a patient with a history of diabetes (Diabetes Mellitus) presenting with no sensation on their toes?

Diabetic Peripheral Neuropathy with Loss of Protective Sensation

This patient has diabetic peripheral neuropathy (DPN) with loss of protective sensation (LOPS), placing them at high risk for foot ulceration and amputation—immediate comprehensive foot examination and risk stratification are required, followed by structured preventive care and patient education. 1

Diagnosis

The absence of sensation on the toes in a patient with diabetes is diagnostic of LOPS, which represents distal symmetric polyneuropathy—the most common manifestation of diabetic neuropathy. 1

Required Clinical Assessment

Perform the following examination immediately:

• 10-g monofilament testing at multiple plantar sites (hallux, metatarsal heads) to confirm LOPS—inability to perceive the monofilament at any site confirms the diagnosis 1
• 128-Hz tuning fork at the dorsum of the great toe to assess vibration sense (large fiber function) 1
• Pinprick or temperature sensation testing to evaluate small fiber function 1
• Ankle reflexes which are typically diminished or absent in DPN 1
• Comprehensive foot inspection for skin integrity, calluses, deformities (claw toes, hammer toes, prominent metatarsals), pre-ulcerative signs, and any existing ulceration 1
• Vascular assessment including palpation of dorsalis pedis and posterior tibial pulses, capillary refill time, and assessment for dependent rubor or pallor on elevation—peripheral arterial disease is present in up to 50% of diabetic foot complications 1

Critical Differential Considerations

Diabetic neuropathy is a diagnosis of exclusion. 1 Rule out other treatable causes of neuropathy:

• Vitamin B12 deficiency (especially if on metformin) 1, 2
• Hypothyroidism 1
• Renal disease 1
• Neurotoxic medications (chemotherapy agents) 1
• Alcohol toxicity 1
• Chronic inflammatory demyelinating neuropathy 1

Electrodiagnostic testing is rarely needed unless the presentation is atypical or non-length-dependent. 1, 2

Risk Stratification

Using the IWGDF Risk Classification System, this patient falls into Category 1 (peripheral neuropathy alone) or higher depending on additional findings: 1

• Category 1: Peripheral neuropathy alone → screen every 6 months 1
• Category 2: Neuropathy + peripheral arterial disease and/or foot deformity → screen every 3-6 months 1
• Category 3: Neuropathy + history of ulcer or amputation → screen every 1-3 months 1

Up to 50% of diabetic peripheral neuropathy is asymptomatic, yet these patients remain at extremely high risk for ulceration and amputation. 1, 2 The absence of symptoms does not indicate absence of risk.

Immediate Management

Preventive Foot Care

• Refer to podiatry or foot care specialist for ongoing preventive care and surveillance, particularly if any additional risk factors are present (deformities, PAD, prior ulceration) 1
• Prescribe therapeutic footwear with adequate cushioning and depth to accommodate any deformities and redistribute plantar pressures 1
• Inspect feet at every clinical visit moving forward—do not wait for annual screening 1

Patient Education (Structured and Specific)

Provide detailed instruction on:

• Daily foot self-examination using a mirror to inspect plantar surfaces for cuts, blisters, redness, or calluses 1
• Never walk barefoot, even indoors—LOPS means they cannot feel injuries as they occur 1
• Check inside shoes before wearing for foreign objects 1
• Proper nail care technique—cut straight across, not too short 1
• Immediate reporting of any skin breaks, color changes, swelling, or warmth to healthcare provider 1
• Avoid extreme temperatures—test bath water with elbow, not foot 1

Glycemic Control

Optimize glucose control to prevent progression—tight glycemic control effectively prevents DPN in type 1 diabetes and modestly slows progression in type 2 diabetes, though it does not reverse established neuronal loss. 1

Address Cardiovascular Risk Factors

• Blood pressure control (target <130/80 mmHg in diabetes) slows retinopathy and likely neuropathy progression 1
• Statin therapy for cardiovascular risk reduction 1
• Smoking cessation if applicable—smoking significantly increases amputation risk 1

Monitoring for Complications

Assess for Autonomic Neuropathy

Screen for symptoms of cardiac autonomic neuropathy (resting tachycardia >100 bpm, orthostatic hypotension) and gastrointestinal neuropathy (gastroparesis, constipation, diarrhea), as these often coexist with DPN. 1

Watch for Charcot Neuro-Osteoarthropathy

Always suspect active Charcot when a patient with diabetes and neuropathy presents with unilateral red, warm, swollen foot with intact skin—this requires immediate knee-high immobilization while diagnostic studies are performed. 1 Temperature difference >2°C between feet measured with infrared thermometry supports the diagnosis. 1

Common Pitfalls

• Assuming absence of pain means absence of neuropathy—50% of DPN is asymptomatic but still carries full ulceration risk 1, 2
• Failing to examine feet at every visit in high-risk patients—visual inspection takes seconds and prevents catastrophic outcomes 1
• Overlooking treatable causes like B12 deficiency—always check before attributing neuropathy solely to diabetes 1, 2
• Inadequate patient education—structured, repeated education with demonstration of techniques is essential, not just verbal instruction 1
• Missing peripheral arterial disease—always assess pulses and consider ankle-brachial index if pulses are diminished, as PAD dramatically worsens prognosis 1