Time-course changes in nerve conduction velocity (NCV) in type 2 diabetes

Abstract

AimChanges in NCV were surveyed over 10 years in type 2 diabetes patients to clarify the time-course relationships between NCV and retinopathy stage and between NCV and HbA1c. In addition, the natural course of diabetic sensorimotor polyneuropathy (DSPN) was discussed based on the findings. MethodsUsing a simple NCV measurement device, NCV (MCV and SCV) was measured once a year over 10 years in 474 patients with type 2 diabetes. These patients were grouped based on the retinopathy stage and HbA1c level in the course to investigate the time-course relationships between the retinopathy stage and NCV and between HbA1c and NCV. ResultsThe retinopathy stage and NCV reduction were strongly correlated, and NCV decreased as retinopathy progressed. On comparison of time-course NCV among the retinopathy stages, continuity of NCV reduction along with the retinopathy progression was noted. Regarding the relationship between HbA1c and NCV, NCV reduction was moderate in the group maintaining HbA1c at a relatively favorable level, but morbid reduction of NCV could not be prevented even though favorable control was maintained. ConclusionNCV reduction is strongly correlated with retinopathy progression from more than 10 years before its manifestation through reaching proliferative retinopathy. It was also suggested that NCV reduction can be attenuated by controlling blood glucose, but the reduction cannot be prevented completely. Based on these findings, DSPN is a progressive complication that starts from an early phase after onset of diabetes and steadily aggravates, keeping step with retinopathy aggravation, and it may be difficult to completely prevent the progression.