What are the key peripheral markers of diabetes and how are they managed?

Peripheral Markers of Diabetes: Key Indicators and Management

All patients with diabetes must undergo annual comprehensive foot examination to identify peripheral neuropathy and peripheral arterial disease (PAD), which are the primary peripheral markers predicting ulceration, amputation, and mortality. 1

Critical Peripheral Markers to Assess

Peripheral Neuropathy Assessment

Loss of protective sensation (LOPS) is the single most important peripheral marker, present as a component cause in 78% of diabetic foot ulcerations. 1 The following tests must be performed:

• 10-g monofilament test at multiple plantar sites (most sensitive bedside test) 1
• At least one additional test to confirm LOPS: 1
  • Vibration perception using 128-Hz tuning fork 1
  • Pinprick discrimination on dorsum of foot 1
  • Tactile sensation with cotton wool 1
  • Achilles tendon reflexes 1

Absent monofilament sensation plus one other abnormal test confirms LOPS. 1 Up to 50% of diabetic peripheral neuropathy may be completely asymptomatic, making objective testing mandatory rather than relying on patient symptoms. 1

Peripheral Arterial Disease Assessment

PAD is present in up to 50% of patients with diabetic foot ulcers and dramatically increases amputation risk. 1, 2 Clinical examination alone is dangerously unreliable—palpable pulses may be present despite significant ischemia. 1, 2

Mandatory vascular assessment includes: 1

• History of claudication or rest pain 1
• Palpation of dorsalis pedis and posterior tibial pulses 1
• Skin temperature (cool indicates ischemia) 1, 2
• Dependent rubor (reddish-purple discoloration when leg dependent) 2
• Pallor on elevation 2
• Capillary refill time and venous filling time 1

Objective testing with Ankle-Brachial Index (ABI) is mandatory even if pulses are palpable. 1, 2 ABI interpretation: 1, 2

• ABI <0.9 = PAD present
• ABI <0.6 = significant ischemia affecting wound healing
• ABI <0.5 or ankle pressure <50 mmHg = critical limb ischemia requiring urgent vascular referral

Critical Pitfall: Medial Arterial Calcification

In diabetes, medial arterial calcification (Mönckeberg sclerosis) causes falsely elevated ABI readings (≥1.3), potentially missing critical ischemia. 1, 2 When ABI ≥1.3, use alternative tests: 1, 2

• Toe-brachial index (TBI ≥0.75 excludes PAD) 1
• Toe systolic pressure (<30 mmHg indicates inability to heal ulcers) 1
• Triphasic pedal Doppler waveforms (presence largely excludes PAD) 1

Risk Stratification and Screening Frequency

Use the IWGDF Risk Classification System to determine follow-up intervals: 1

• Category 0 (no neuropathy): Annual examination 1
• Category 1 (neuropathy present): Every 6 months 1
• Category 2 (neuropathy + PAD and/or foot deformity): Every 3-6 months 1
• Category 3 (neuropathy + history of ulcer/amputation): Every 1-3 months 1

Additional High-Risk Markers

Screen for these factors that increase ulceration and amputation risk: 1

• Foot deformities (bunions, hammertoes, Charcot joint, prominent metatarsals) 1
• Pre-ulcerative calluses or corns 1
• Prior ulceration or amputation 1
• End-stage renal disease or dialysis 1
• Retinopathy 1
• Poor glycemic control 1
• Smoking 1

Management Priorities

Immediate Vascular Referral Required

Urgent referral to vascular surgery is mandatory when: 2

• ABI <0.5 2
• Ankle pressure <50 mmHg 2
• Toe pressure <30 mmHg 2
• TcPO2 <25 mmHg 2

Revascularization should be attempted before considering amputation. 2

Neuropathic Pain Management

For symptomatic neuropathy, pregabalin or duloxetine are recommended as initial pharmacologic treatments. 1 Optimizing glucose control prevents or delays neuropathy development in type 1 diabetes and slows progression in type 2 diabetes. 1

Patient Education

Structured, repeated education is essential and must cover: 1

• Daily foot inspection for injuries, color changes, or pre-ulcerative signs 1
• Proper footwear (seamless socks, well-fitting shoes) 1
• Never walking barefoot 1
• Daily foot washing with water <37°C 1
• Immediate reporting of any foot problems 1

Key Clinical Pitfalls to Avoid

Never assume normal perfusion based on palpable pulses alone—this is a dangerous error that can lead to missed critical ischemia and preventable amputations. 2 Never rely on patient symptoms alone—asymptomatic neuropathy and PAD are extremely common and can only be detected through systematic objective testing. 1 Never delay vascular referral when objective testing indicates critical ischemia, as time to revascularization directly impacts limb salvage rates. 2