Ultrasound-measured enlargement of the cross-sectional area of the median nerve as a marker for early neuronal lesions in pediatric type 1 diabetes.

Diabetic neuropathy can develop early in type 1 diabetes (T1D), but reliable non-invasive markers for subclinical nerve damage due to metabolic alterations in children and adolescents are lacking. We conducted a controlled cross-sectional study of 73 patients with T1D (8-16 years, diabetes duration > 6 months) and 71 age-matched controls to identify abnormalities of the median nerve using high-resolution ultrasound. Cross-sectional area (CSA) of the median nerve was measured at the wrist and mid-forearm and related to body surface area (BSA) and glycemic control (HbA1c) using linear regression models. CSA at the wrist did not differ between groups, whereas CSA at the mid-forearm was higher in children with T1D reaching statistical significance in those with HbA1c > 9%. Although CSA correlated positively with BSA across all participants, in patients with T1D, it remained significantly associated with HbA1c after adjustment for BSA (regression coefficient 0.217 mm² per % HbA1c [95% CI 0.073-0.361], p = 0.004; for BSA: 4.226 mm² per m² [95% CI 2.899-5.554], p < 0.001), even in those with diabetes duration of less than 2 years. These findings indicate that, despite normal examination, ultrasound can detect enlargement of the median nerve in pediatric T1D, which is associated with poor metabolic control.