Abstract
OBJECTIVE: A prospective ultrasound study to analyze nerve size and its modifying factors in type 1 and type 2 diabetes mellitus. METHODS: The cross-sectional areas (CSAs) of motor and sensory nerves in both upper and lower limbs were measured at 14 measurement points, using high resolution ultrasound in 26 patients with type 1 and 76 patients with type 2 diabetes, and in 50 control subjects. All diabetic patients underwent electrophysiological assessment to check for the presence of polyneuropathy. RESULTS: Significant mild/moderate diffuse nerve enlargement was demonstrated in type 2 diabetes, more pronounced at compression sites versus non-compression sites, and on the upper limbs versus lower limbs (p value for pooled DM2 v. control group: <0.001). In type 1 diabetes, nerve enlargement was found only at one compression site (median nerve wrist; p = 0.002). No significant difference was found between patients with or without polyneuropathy. CONCLUSIONS: The primary predictors of nerve size in diabetes are anatomical location (i.e. compression sites versus non-compression sites, upper versus lower limbs) and type of diabetes. Changes occur before the electrophysiological signs of polyneuropathy are detected. SIGNIFICANCE: Nerve ultrasound may contribute to early recognition of the neuropathic complications of diabetes.