Ultrasound Assessment of Sciatic Nerve and Inferior Gluteal Artery in Diabetic Peripheral Neuropathy(DPN): Association With a Target Gene

This study is a prospective, observational, cross-sectional investigation designed to explore the early diagnostic value of high-frequency ultrasound in patients with type 2 diabetic peripheral neuropathy(DPN) by integrating bioinformatics-derived molecular markers. The study aims to validate a "Structure-function-molecule" cascade hypothesis for DPN progression.

Background and Rationale:

DPN is a highly disabling complication of diabetes with no current disease-modifying treatment, underscoring the urgent need for early detection. Prior work by our group found that elevated N/OFQ in DPN rats was associated with reduced limb blood flow, mediated by Membrane Metallo-Endopeptidase(MME). Shifting the focus from vascular to neural mechanisms, the present study employed independent bioinformatics analysis and identified MMP9 as a core target gene linking N/OFQ to DPN-related nerve damage, enriched in the AMPK signaling pathway. This clinical study therefore aims to validate MMP9 as a serum biomarker and examine its correlation with sciatic nerve cross-sectional area and inferior gluteal artery blood flow velocity on ultrasound across DPN severity grades.

Study Design and Participants:

A total of 120 adult patients with type 2 diabetes mellitus, diagnosed according to World Health Organization criteria, will be consecutively recruited from the Endocrinology Department of the Second Hospital of Shanxi Medical University.

Grouping and Assessments:

Participants will be stratified into three distinct severity grades based on the Toronto Clinical Scoring System(TCSS): Grade 1 (0-5 points), Grade 2 (6-9 points), Grade 3 (≥10 points). Each participant will undergo the following integrated assessments:

1. Demographic and Clinical Data Collection: Records include age, sex, body mass index, diabetes duration, HbA1c, and lipid profile.
2. Ultrasound Examination: With the patient in a lateral decubitus position (hip and knee flexed), a high-frequency linear probe will be placed at the midpoint between the ischial tuberosity and the greater trochanter to visualize the sciatic nerve. Color and pulsed-wave Doppler will subsequently measure blood flow velocity in the inferior gluteal artery.
3. Serum Biomarker Detection: Venous blood samples will be collected and centrifuged. Serum levels of the target protein MMP9 will be quantified.
4. Nerve Conduction Studies:

Standard electrophysiological parameters, including motor nerve conduction velocity(MNCV) and sensory nerve conduction velocity(SNCV) for the lower limbs, will be recorded for correlation.

Outcome Measures and Statistical Analysis:

Statistical analysis will employ ANOVA or Kruskal-Wallis tests for inter-group comparisons. Pearson or Spearman correlation coefficients will quantify the relationships among nerve structure, blood flow, and molecular markers. The combined diagnostic performance will be assessed using receiver operating characteristic (ROC) curves and logistic regression models to calculate the area under the curve (AUC). The study hypothesizes that a multimodal diagnostic model integrating imaging and serum biomarkers will provide superior sensitivity and specificity for early DPN detection compared to single-modality assessments alone.