Introduction: Hypoglycemia in diabetic patients has been recognized as a risk factor for cardiac events in previous studies. Though it is considered that high sympathetic activity resulting from lowered glucose levels causes arrhythmias or ischemic attacks, there is little evidence in the real world.
Methods: We recorded and analyzed the blood glucose level and electrocardiograms in 32 diabetic subjects (16 males; age, 63±17 years; diabetes duration, 16±14 years) that were taking hypoglycemic agents. A continuous glucose monitoring system and 12-lead Holter monitor were simultaneously used for at least 24 hours. A power spectrum frequency analysis of the electrocardiograms was performed by computer software. The LF/HF power during sleep was divided by the total LF/HF power to evaluate the alterations at night.
Results: In 6 patients, hypoglycemia of under 70mg/dl during sleep was recorded. No significant increase in any arrhythmias was observed in the hypoglycemic group. The frequency analysis revealed that the sleeping LF/HF alterations in the hypoglycemic patients were higher than those in the other patient groups (1.00±0.06 vs. 0.85±0.25, p=0.04).
Conclusions: Hypoglycemia in type-2 diabetic patients may cause higher sympathetic activity during sleep.