A 5-year follow-up visual evoked potentials and nerve conduction study in young adults with type 1 diabetes mellitus

ABSTRACT

Central nervous system impairment is common in diabetic patients, even in the early stages of the disease, and could be associated with peripheral neuropathy. The aims of this study were to prospectively investigate central nerve conduction in young adults with type 1 diabetes using pattern-reversal visual evoked potentials (PRVEP) and to determine how those results were related to clinical risk factors and the parameters of the peripheral nerve conduction study (NCS). A total of 36 type 1 diabetic patients (15 males) 5-24 years of age (mean 14.5 ± 4.7) underwent PRVEP and NCS annually for five years. For comparison, 39 healthy age and sex matched individuals (mean 14.8 ± 5.0) were evaluated as the control group. The P100 latencies of the PRVEP were prolonged at the study entry in the patients compared with the controls (p< 0.001). Significant correlations were not found between any of the parameters of PRVEP and the glycosylated hemoglobin levels; however, the changes in the parameters of the peripheral NCS were well correlated with metabolic control. The latencies and amplitudes of the P100 were not related to the majority of the parameters of the NCS. A prolonged PRVEP latency may be a sign of optic pathway dysfunction, which begins before apparent diabetic retinopathy. Poor glycemic control proved to be an important risk factor over the 5 years in terms of its relation to the development of peripheral neural pathway abnormalities. However, once central conduction was delayed, its changes were poorly related to diabetic control and the attributes of the peripheral nerve conduction study over the 5-year follow-up.