What is the World Health Organization (WHO) classification of diabetic neuropathy?

WHO Classification of Diabetic Neuropathy

There is no specific World Health Organization (WHO) classification system for diabetic neuropathy cited in current clinical guidelines. The American Diabetes Association and other major medical societies use a descriptive classification system that categorizes diabetic neuropathies based on anatomical distribution and clinical presentation rather than a WHO-designated framework 1, 2.

Current Classification Framework

Diabetic neuropathies are classified as a heterogeneous group of disorders with diverse clinical manifestations, rather than following a single WHO classification scheme 1. The most widely accepted approach categorizes diabetic neuropathy into four main types 3:

1. Distal Symmetric Polyneuropathy (DSP)

• The most common form, affecting approximately 50% of patients with diabetes 4
• Characterized by length-dependent sensory loss starting in the toes and feet with gradual ascending progression 2, 5
• Involves both small-fiber dysfunction (burning pain, tingling, dysesthesia) and large-fiber dysfunction (numbness, loss of vibration sense, loss of protective sensation) 1, 2
• Up to 50% of cases may be asymptomatic, making systematic screening essential 1, 2

2. Autonomic Neuropathy

• Affects cardiovascular, gastrointestinal, and urogenital systems 3
• Cardiovascular manifestations include resting tachycardia, orthostatic hypotension (systolic BP drop >20 mmHg or diastolic drop >10 mmHg), and silent myocardial ischemia 5
• Gastrointestinal symptoms include gastroparesis, esophageal dysmotility, constipation, diarrhea, and fecal incontinence 5
• Urogenital manifestations include erectile dysfunction, retrograde ejaculation, bladder dysfunction with urinary incontinence, and nocturia 5
• Sudomotor dysfunction presents as altered sweating patterns and dry cracked skin 5

3. Focal and Multifocal Neuropathies

• Subacute-onset conditions that are frequently painful but generally self-limited 6
• Can be sensory predominant (symmetric) or motor predominant (asymmetric) 6

4. Radiculoplexus Neuropathies

• Less common forms affecting nerve roots and plexuses 3

Diagnostic Approach

Diabetic neuropathy is fundamentally a diagnosis of exclusion, requiring elimination of other treatable causes including toxins, neurotoxic medications, vitamin B12 deficiency, hypothyroidism, renal disease, malignancies, infections, chronic inflammatory demyelinating neuropathy, and inherited neuropathies 1, 2.

Screening Recommendations

• Type 1 diabetes: Begin screening 5 years after diagnosis 1, 2
• Type 2 diabetes: Screen at diagnosis 1, 2
• Frequency: Annual screening thereafter for both types 1, 2

Clinical Assessment Components

• Small-fiber function: Pinprick and temperature sensation tests 1, 2
• Large-fiber function: Vibration perception using 128-Hz tuning fork and lower-extremity reflexes 1, 2
• Protective sensation: 10-g monofilament testing to identify feet at risk for ulceration 1, 2

Common Pitfalls

• Assuming all neuropathy in diabetics is diabetic neuropathy: Other causes must be systematically excluded, particularly chronic inflammatory demyelinating polyneuropathy (CIDP), which occurs with two-fold increased risk in diabetes and requires immunotherapy 7
• Missing asymptomatic cases: Since 50% of DPN is asymptomatic, relying on patient complaints alone will miss half of cases at risk for foot ulceration and amputation 1, 2
• Overlooking autonomic neuropathy: Systematic assessment for autonomic symptoms (orthostatic dizziness, syncope, dry cracked skin) should occur annually, particularly in patients with other microvascular complications 1, 5