A 5-yr follow-up nerve conduction study for the detection of subclinical diabetic neuropathy in children with newly diagnosed insulin-dependent diabetes mellitus.

OBJECTIVE: To investigate the changes of peripheral nerve conduction in children with insulin-dependent diabetes mellitus (IDDM) prospectively from diagnosis and to know how those results were related to clinical risk factors.
METHODS: A total of 37 patients (14 males and 23 females) aged 3-19 yr (mean 12.0 ± 3.7) with newly diagnosed IDDM underwent bilateral nerve conduction studies (NCS) of median, ulnar, posterior tibial, peroneal, and sural nerves annually for 5 yr.
RESULTS: In all, 12 patients (32.4%) showed electrophysiological evidence of polyneuropathy in at least two different nerves including the sural nerve at the diagnosis of IDDM; 20 patients (54%) had multiple (≥2) abnormalities in parameters of NCS. The most common abnormal parameters at the diagnosis were conduction velocities of peroneal motor and sural nerves. In sequential NCS over 5 yr, the percentage of abnormal nerve conduction velocities rose except within the sural nerve. Poor metabolic control, height, duration of diabetes, and older age of onset were related to the changes of parameters of NCS over 5 yr. Among those risk factors, the duration of diabetes and sustained hyperglycemia affected the parameters of NCS more frequently than others.
CONCLUSIONS: Children with IDDM frequently have nerve conduction abnormalities without clinical neuropathy at initial diagnosis. The frequency of abnormalities of any attribute of nerve conduction increased over the 5 yr follow-up. The duration of diabetes and poor glycemic control proved to be more important risk factors over 5 yr as related to the development of subclinical neuropathy.