Qiao-Ying You, Bing Xu, Fu-Yuan Zuge
Keywords
Asymptomatic hypoglycemia • Heart rate variability • Spectral analysis • Cardiac autonomic dysfunction • Type 2 diabetes
Abstract
Aim Current knowledge regarding the changes in cardiac autonomic nerve function during asymptomatic hypoglycemia in type 2 diabetes (T2D) is limited. This study aimed to investigate the association between the severity of nocturnal asymptomatic hypoglycemia and short-term heart rate variability (HRV) changes in patients with T2D.
Methods Comparison of changes was performed in a short-term time domain and frequency domain analysis of HRV during nocturnal asymptomatic hypoglycemia [interstitial glucose (IG) ≤ 3.5 mmol/L] and during euglycemia in T2D subjects treated with insulin (n = 58). Further stratification was performed according to the degree of hypoglycemia. All patients underwent 72 h of simultaneous Holter and continuous interstitial glucose monitoring (CGM).
Results Fifty-two nocturnal asymptomatic hypoglycemia episodes were included in the spectral analysis of HRV in the participants. In the hypoglycemic (IG < 3 mmol/L) subjects, the short-term time domain parameters (standard deviation of normal R-R intervals (SDNN), RMSSD (the square root of the mean squared difference of successive RR intervals)) and normalized high-frequency (HF) were significantly lower than those during the matched euglycemic period (IG
5–10 mmol/L) (all p < 0.01), and the normalized low-frequency (LF)/HF ratio was increased (p < 0.05). In the hypoglycemic (≤ 3 IG ≤ 3.5 mmol/L) subjects, although HF was significantly lower than that in the euglycemic subjects (p < 0.01), no differences were observed in the SDNN, RMSSD, or the LF/HF ratio.
Conclusions The spectral analysis of HRV showed that reduced HRV was associated with the severity of nocturnal asymptomatic hypoglycemia; severe hypoglycemia aggravates the cardiac autonomic nerve imbalance.
