Nerve conduction abnormalities in different stages of glucose intolerance

To look for changes in nerve conduction velocity (NCV) in early stages of glucose intolerance, i.e. in impaired glucose tolerance (IGT) and in asymptomatic newly diagnosed Type 2 diabetic subjects (NDD).

A total of 225 subjects were categorized as: Group 1: Subjects with normal glucose tolerance (NGT), Group 2: IGT subjects and Group 3: NDD subjects. Motor (MCV) and Sensory nerve Conduction Velocity (SCV) measurements were done.

The mean MCV was significantly lower in the NDD group (47 +/- 5 m/s) when compared with the other two groups (IGT=50 +/-4.5 m/s; NGT= 53 +/- 4 m/s; P=0.0001). The IGT group of subjects also exhibited a significantly lower mean MCV when compared with the NGT subjects (P=0.0001). The mean SCV in the NDD group (42+10 m/s) was also significantly lower (P< 0.0007) than the NGT (46+6 m/s) and the IGT (48+10 m/s) groups. No significant difference in the mean SCV between the NGT and IGT groups was noted. In the multiple linear regression analysis both age and male gender were the risk factors for abnormal MCV and SCV. Abnormal MCV was found to be associated with 2-hr post glucose levels (R2 = 14.5%), while HbA1c (R2 = 4.9%) contributed towards abnormal SCV.

Abnormal NCV is a common finding in NDD subjects. Slower mean MCV demonstrated by IGT subjects, calls for early screening of these subjects for complications.