ESPE Abstracts

Background: There is an urgent need for better detection of early subclinical manifestations of microvascular complications of diabetes such as peripheral neuropathy (DPN), which already occur in children. The gold standard for the diagnosis of DPN is the measurement of nerve conduction velocity (NCV), which, however, can only detect changes in the large myelinated fibres. At the initial stage of DPN, small, unmyelinated nerve fibres are damaged. High-resolution ultrasound of peripheral nerves is used to measure their cross-sectional area (CSA), which represents the small fibres. In adults with type 1 diabetes (T1D), studies have shown an increase in CSA as an early sign of DPN. The aim of this study is to establish normative data in healthy children and to identify DPN at an asymptomatic disease stage and the contributing factors.

Methods: In 40 patients with T1D (12-15 years) and 34 controls, the CSA of the median nerve was measured sonographically proximal to the flexor retinaculum (R1) and in the middle of the forearm (R2). The association of CSA at R2 with body surface area (BSA), BMI and HbA1c was tested with standard statistical methods, e.g. multivariant analysis.

Results: In both groups, CSA was predicted by BSA or BMI, but the latter was significant only in children with T1D. CSA was larger in the diabetes than in the control group (P = 0.009), while in a subgroup of T1D with BMI below 60^th percentile, this was no longer significant. HbA1c level correlated with nerve thickness adjusted for BSA (CSA/BSA) and explained 47% of the additional gain in nerve area (r =0.47, P = 0.0025). A subgroup of children with elevated CSA/BSA (P = 0.0035), despite satisfactory glycaemic control (HbA1c <8%, no correlation with CSA/BSA), was identified, which encompassed children with diabetes onset before the age of 8 years.

Discussion: In children with T1D, median nerve thickness is increased; its CSA is related to body surface, adiposity and HbA1c level. Young age at diabetes onset appears to contribute to DPN. The present data suggest that early small fibre neuropathy, as represented by thickened CSA/BSA, can be mitigated by a normal BMI and good glycaemic control. In summary, ultrasonography of the median nerve, where increased thickness predicts an early stage of neuropathy, complements NCV of the peroneal nerve, associated with DNP of the large myelinated fibres. Both will allow the search for early interventions to prevent clinical manifestation of DNP.