Diagnostic value of heart rate-based methods for assessing cardiac autonomic neuropathy in prediabetes and diabetes.

This study tested the ability of simple heart rate (HR)-based measures-namely, resting HR variability (HRV), post-exercise HRV, and HR recovery (HRR)-to identify cardiovascular autonomic neuropathy (CAN) in individuals with prediabetes and type 2 diabetes (T2D). Fifty subjects with T2D or prediabetes participated in the study. CAN was diagnosed using five cardiovascular reflex tests: HR response to Valsalva, deep breathing, and standing; and blood pressure response to sustained handgrip and standing. Resting HRV was evaluated using time- (SDNN, RMSSD) and frequency-domain analysis (total power, low-[LF] and high-frequency power [HF]). Post-exercise HRV and HRR were assessed over 2 minutes after the Incremental Shuttle Walking Test. HRR was calculated as the difference between peak HR and HR at 1 and 2 min post-test (HRR1min, HRR2min). ROC curve analysis showed that the resting HF-HRV index had the strongest diagnostic performance among resting indices (sensitivity = 67.9%, specificity = 86.4%, AUC = 0.755, p = 0.001), while HRR2min showed the best performance among the post-exercise indices (AUC = 0.672, p = 0.042). Overall, resting HRV indices consistently outperformed post-exercise HRR and HRV indices in diagnostic performance. The results suggest that resting HRV has strong potential for detecting CAN in individuals with prediabetes and T2D, and could be incorporated into CAN screening protocols.