Point-of-care sural nerve conduction could predict the presence of cardiovascular autonomic neuropathy in type 1 diabetes mellitus

Aims: Assessment for cardiovascular autonomic neuropathy (CAN) in patients with type 1 diabetes mellitus remains time-consuming in the clinical setting. We aimed to examine the diagnostic performance of a portable point-of-care diagnostic tool (POCD) for assessing sural nerve conduction during the screening of CAN.

Methods: Nerve amplitude (AMP_POCD ) and conduction velocity (CV_POCD ) were measured in a cross-sectional study including 198 asymptomatic patients with type 1 diabetes. CAN was diagnosed by the Ewing score and power spectral heart rate [low-frequency (LF) and high-frequency (HF) activity]. Diagnostic accuracy was determined by ROC curves.

Results: CV_POCD and AMP_POCD showed positive correlations with LF and HF, and a negative correlation with age. Overall, AMP_POCD had an 81.7% accuracy in identifying CAN [AUC = 0.817 (95% CI 0.692-0.942)] with an AMP_POCD ≤6 μV showing 90% sensitivity and 73% specificity. In a stepwise binary logistic regression analysis, the model (R² : 0.297; P < 0.001) retained the duration of type 1 diabetes [β: 1.131 (95% CI: 1.051-1.216); P = 0.001) and A_1c [β: 2.131 (95% CI: 1.060-4.283); P = 0.034) as significant predictors of CAN. The combination of AMP_POCD ≤6 μV + a type 1 diabetes duration of ≥8 years maximized the sensitivity, showing a diagnostic performance of 87% [AUC = 0.867 (95% CI 0.769-0.965)] with 90%, 76%, and 99%, sensitivity, specificity, and NPV, respectively. Adding A_1c ≥ 7% to this model maintained accuracy [AUC = 0.867 (95% CI: 0.788-0.963) and NPV (99%), while increasing specificity to 84%.

Conclusions: The combination of AMP_POCD with A_1c and the duration of type 1 diabetes mellitus showed a good performance for the detection of asymptomatic CAN, making POCD an easy and rapid test for its routine screening in the clinical setting.