Study of Electrophysiological Changes in Sensory Nerves Among Diabetic Smokers

Neuropathy is one of the most troublesome complication affecting individuals with diabetes. The resultant loss of function in peripheral nerves causes loss of protective sensations and impairs patient's ability to perceive incipient or even apparent ulcerations in the feet.

This study was undertaken to test the hypothesis of alteration in electrophysiological parameters of nerve before actual manifestations of neuropathy in type 2 diabetic patients and to analyse the effect of smoking on Sensory Nerve Conduction Velocity (SNCV) of diabetic subjects.

One hundred and twenty diagnosed diabetics were taken as cases while 30 healthy non diabetics were taken as control. Case group was divided into diabetic non-smoker and diabetic smoker. Diabetic smoker were further subdivided into light smoker, moderate smoker and heavy smoker according to smoking index. After detailed history and physical examination SNCV of median and ulnar nerve in upper limb and sural nerve in lower limb was performed.

On comparison of SNCV of median and ulnar nerve of upper limb and sural nerve of lower limb between control and diabetic non-smoker only sural nerve of diabetic non smoker showed significant bilateral decrease. There was significant bilateral decrease in SNCV of median and ulnar nerve of diabetic heavy smoker when compared to control and diabetic non smoker. Similarly, SNCV of sural nerve of diabetic heavy smoker was significantly decreased when compared with control, diabetic non-smoker, diabetic light and moderate smoker. A negative and statistically significant correlation was found between SNCV and smoking index.

Present study indicates that nerves of lower limbs are more susceptible to diabetic assault as compared to upper limb suggesting that long nerves are commonly affected. Also, apart from duration and severity of diabetes, smoking itself is an independent factor for diabetic neuropathy.