Peripheral Nerve Conduction and Vitamin B12 in Type 2 Diabetics with and without Neuropathy

Background: Diabetic peripheral neuropathy is the most common chronic complication of type 2 diabetes mellitus. B12 is needed for myelin maintenance, and its status may influence nerve function in type 2 diabetics. Material and Methods: This study recruited patients with type 2 diabetes at a tertiary care hospital in northern India. They were divided into two groups, patients with neuropathy, and patients without neuropathy. Body mass index, blood pressure, fasting and post prandial blood sugar, glycated haemoglobin, serum lipid profile and serum vitamin B12 were measured, and nerve conduction velocities were recorded. Groups were compared and linear regression of nerve conduction velocity on serum vitamin B12 was also performed. Results: Body mass index was higher in the neuropathy group, while age and blood pressure did not differ. This group had higher total cholesterol, triglyceride and low density lipoprotein cholesterol, and markedly lower high density lipoprotein cholesterol, whereas very low density lipoprotein cholesterol did not differ significantly. Glycated haemoglobin was higher and serum vitamin B12 lower in the neuropathy group. Among patients with neuropathy, serum vitamin B12 predicted conduction velocity in both motor and sensory nerves, with a stronger association for motor nerves. Conclusion: Serum vitamin B12 was lower in patients with diabetic peripheral neuropathy and showed a positive relationship with both motor and sensory conduction velocity, accounting for about one fifth of the variance in motor conduction.

Keywords: diabetic peripheral neuropathy; nerve conduction velocity; type 2 diabetes mellitus; vitamin B12.