Low peripheral nerve conduction velocities and amplitudes are strongly related to diabetic microvascular complications in type 1 diabetes: the EURODIAB Prospective Complications Study

Objective: Slow nerve conduction velocity and reduction in response amplitude are objective hallmarks of diabetic sensorimotor polyneuropathy. As subjective or clinical indicators of neuropathy do not always match well with the presence of abnormal nerve physiology tests, we evaluated associations to nerve conduction in patients with type 1 diabetes. Methods: Nerve conduction studies were performed in the distal sural and ulnar sensory nerves and the peroneal motor nerve in 456 individuals with type 1 diabetes who participated in the follow-up visit of the EURODIAB Prospective Complications Study (EPCS). We used multivariate regression models to describe associations to decreased nerve conduction measures. Results: In addition to an effect of duration of diabetes and HbA1c, which were both associated with low nerve conduction velocity and response amplitude, we found the presence of nephropathy, retinopathy or a clinical diagnosis of neuropathy were associated with low nerve conduction velocity and amplitude. In the case of non-proliferative retinopathy, odds ratio for being in lowest tertile were 2.30 (1.13; 4.67) for nerve conduction velocity. A similar odds ratio was found for each 2% difference in HbA1c (OR: 2.39 (1.68; 3.41). Conclusions: We show that the presence of other microvascular diabetic complications, together with diabetes duration, and HbA1c, are associated to low nerve conduction velocity and amplitude response; and that cardiovascular disease or risk factors do not seem to be associated to these measures