Abstract 12483: Influence of Spontaneous Nocturnal Hypoglycemia on Cardiac Autonomic Regulation in Patients with Type 1 Diabetes
Introduction: Experimental clamp studies have suggested that hypoglycemia Results in reduction of cardiac vagal control in patients with type 1 diabetes. However, the data on the influence of spontaneous nocturnal hypoglycemia on cardiac autonomic regulation in a “real life” situation in these patients is limited.
Methods: Adults with type 1 diabetes (n=37) underwent continuous glucose monitoring via a subcutaneous sensor and RR-interval or ECG recording for three nights. Heart rate variability was analyzed during both hypoglycemia (glucose<3.5 mmol/l) with a minimum length of 20 minutes and a control nonhypoglycemic period (glucose>3.9 mmol/l) with an equal duration and time of night.
Results: The duration of hypoglycemia-control pairs (n=18) ranged from 20 to 190 minutes (mean 71min). Heart rate (62±7 beats/min during normoglycemia versus 63±9 beats/min during hypoglycemia, p=0.30) or the high-frequency component of heart rate power spectrum (2002±1965 ms2 versus 1336±1506 ms2, respectively, p=0.26) did not change significantly during hypoglycemia. Hypoglycemia resulted in significant decrease in the low-frequency component of heart rate variability (2134±1635 ms2 versus 1169±1029 ms2, respectively, p=0.006). The decline in glucose concentration had a significant positive correlation with the decrease of the low-frequency component of heart rate variability (r=0.48, p=0.04).
Conclusions:Spontaneous nocturnal hypoglycemia in patients with type 1 diabetes results in changes of cardiac autonomic regulation, which are best explained by excessive sympathetic activation without concomitant significant changes in vagal outflow. These changes may have contribution to the risk for “dead in bed” syndrome in these patients.
- © 2010 by American Heart Association, Inc.