MNAMS, DNB (General Medicine), Certified in Evidence Based Diabetes Management, MBBS
Internal Medicine Specialist
Diabetic neuropathy. What is it?
Uncontrolled diabetes can lead to a number of long term complications, which can be broadly divided into two categories:
1. Microvascular - those which affect the smaller vessels
2. Macrovascular - those which affect the larger blood vessels.
The microvascular complications include - neuropathy (affecting the small blood vessels of the nerves), retinopathy (affecting the small blood vessels of the retina/eye) and nephropathy (affecting the small blood vessels supplying the kidney).
The macrovascular complications include - cardiovascular disease (for example coronary artery disease), cerebrovascular disease (for example stroke) and peripheral vascular disease.
Neuropathy is one of the commonest complications of long term uncontrolled diabetes mellitus. It is estimated that between 60 and 70 percent of people with diabetes have some form of neuropathy, and a number of questions in the forum often deal with this.
Why does diabetic neuropathy occur?
Persistantly raised blood sugar can damage nerve fibers throughout the body, however, diabetic neuropathy commonly damages nerves in the legs and feet (commonly referred to as the gloves and stockings distribution). Duration of diabetes, age, cigarette smoking, high blood pressure and deranged lipid profile are risk factors for diabetic neuropathy.
It can affect the sensory system (altered sensation), motor system (causes muscle weakness) and autonomic system (can cause dizziness, reduced sweating).
How is diabetic neuropathy classified?
As mentioned above, it may be classifed based on the system involved - sensory, motor or autonomic (the involuntary system). Neuropathy can also be classified as per the areas of nerve involvement
Mononeuropathy - single nerve involvement
Mononeuritis multiplex - multiple lesions at different levels
Polyneuropathy - generalised involvement
Radiculopathy - nerve root involvement (" electric shock" like sensation)
Entrapment neuropathy - in thi condition a partcular nerve is trapped, ususally in an anatomical channel (eg carpal tunnel syndrome)
Diabetic amyotrophy - in this condition there is weakness followed by wasting of pelvic and femoral muscles (hip and lower limbs), either unilaterally or bilaterally, with associated pain. It can be severely disabling.
What are the clinical features?
Diabetic neuropathy may be asymptomatic initially. Common symptoms are
- numbness and tingling of extremities
- dysesthesis (abnormal sensations)
- burning pain, specially noted in the extremities
- muscle weakness
- diarrhea and constipation
- urinary incontinence
- erectile dysfunction
How is it diagnosed?
Clinical features, are highly suggestive of diabetic neuropathy. Clinicians may use semmes-weinstein monofilament and vibration tests to diagnose this condition, however, nerve conduction velocity tests (usually of all the 4 limbs), give a definitive diagnosis.
Treatment of this condition
Optimal glucose control is advised, to prevent the long term vascular complications.
The medications available are
Tricyclic antidepressants - amitryptilline, nortryptilline
Selective serotonin reuptake inhibitor- fluoxetine, paroxetine, escitalopram, sertraline
Serotonin-norepinephrine reuptake inhibitors - duloxetine, venlafaxine,
Antiepileptic drugs - gabapentin, pregabalin, carbamazepine
Others - vitamin b12 (methylcobalamine), alpha lipoic acid. Monochromatic infrared photo energy treatment (mire) has been shown to be an effective therapy in reducing and often eliminating pain associated with diabetic neuropathy. Opioids may help in severe pain. Physiotherapy (tens, ifc) may be helpful
A single or combination of drugs may be used. Duloxetine and pregabalin are the only two fda approved drug for peripheral diabetic neuropathy.
Complications of diabetic neuropathy
Since, the normal sensation is affected in neuropathy, small injuries may lead to development of large ulcerations, which may lead to severe infections. Sometimes, amputation may be needed. Development of callous in the foot is common. Charcot's foot is a common complication. Erectile dysfunction is both a symptom and complication in neuropathy (autonomic)
Other conditions mimicing diabetic neuropathy
Metformin is a medication given in diabetes, however, it can cause vitamin b12 deficiency, which can lead to similar symptoms. Osteoarthritis can lead to severe pain and disability.
Suggestions in diabetic neuropathy
If a person is detected with diabetic neuroapathym eye check up and renal check up are advised to rule out retinopathy and nephropathy respectively. It is important to check the fasting and post prandial blood sugar every 15 days and hba1c every 3 months. Iff possible self monitoring of blood glucose (smbg) is advised.