Q 2.7. Metabolic neuropathies. Diabetic neuropathy.

Let’s start with a clinical case:

Patient Profile:

• Initials: J.D.
• Age: 58 years
• Sex: Male
• Occupation: Retired accountant

Presenting Complaint: J.D. presents with a 6-month history of progressive numbness and tingling in his feet, which has recently started to affect his hands. He describes the sensation as “walking on cotton” and reports occasional sharp, shooting pains in his toes.

Medical History:

• Type 2 diabetes mellitus diagnosed 10 years ago, managed with metformin and lifestyle modifications.
• Hypertension controlled with an ACE inhibitor.
• Hyperlipidemia treated with a statin.

Examination Findings:

• Bilateral decreased sensation to light touch and pinprick in a “stocking-glove” distribution.
• Diminished ankle reflexes.
• No ulcers or deformities noted on foot examination.

Investigations:

• Fasting blood glucose:  9 mmol/L (162 mg/dL)
• HbA1c: 8.4%
• Nerve conduction studies confirm reduced conduction velocities and amplitude in peripheral nerves, consistent with polyneuropathy.

Diagnosis: Diabetic polyneuropathy, likely due to chronic hyperglycemia and diabetes-related microvascular damage.

Management Plan:

• Optimization of glycemic control with adjustment of antidiabetic medications.
• Introduction of pregabalin for neuropathic pain management.
• Regular podiatry assessments to monitor for foot complications.
• Patient education on foot care and monitoring for signs of infection or injury.

Prognosis: With improved glycemic control and appropriate management of symptoms, J.D.’s quality of life can be significantly enhanced. However, the chronic nature of diabetic polyneuropathy means that ongoing monitoring and management will be necessary to prevent complications and progression of the disease.

1. Metabolic Neuropathies:
   • These neuropathies result from metabolic disturbances affecting nerve function.
   • Diabetic neuropathy is a prominent example within this category.
   • Metabolic mechanisms play a crucial role in the development of neuropathy.

2. Diabetic Neuropathy:
   • Definition: Diabetic neuropathy refers to nerve damage caused by diabetes mellitus.
   • Epidemiology:
     • Most common neurologic complication of diabetes.
     • Gradual loss of integrity of the longest nerve fibers.
     • Symptoms begin distally and symmetrically in the toes and feet.
   • Clinical Features:
     • Distal Symmetric Polyneuropathy (DSPN):
       • Often synonymous with diabetic neuropathy.
       • Major cause of morbidity.
       • Linked to glycemic control.
     • Type 1 vs. Type 2 Diabetes:
       • Neuropathy in type 1 diabetes closely linked to glycemic control.
       • Neuropathy in type 2 diabetes linked to:
         • Dyslipidemia.
         • Central obesity.
         • Hypertension.
         • Insulin resistance.
         • Glucose control.
   • Diagnosis:
     • Clinical examination.
     • Objective point-of-care devices.
   • Pathophysiology:
     • Multiple pathways involved:
       • Metabolic.
       • Vascular.
       • Immunologic.
       • Neurohormonal growth factor deficiency.
       • Genetic.
       • Extracellular matrix remodeling.
     • Metabolic Mechanisms:
       • Implicated in diabetic neuropathy.
       • Includes dyslipidemia, bioenergetics, and oxidative damage.
       • Mitochondrial dysfunction plays a role.
   • Management:
     • Focus on glycemic control.
     • Symptomatic relief.
     • Multidisciplinary approach.