BERLIN – A hypoglycemic event and a high rate of glucose excursions were associated with an increased rate of ventricular tachycardia, in a study of 30 patients with type 2 diabetes and a history of cardiovascular disease.
The findings highlight the potentially important role that glycemic excursions and hypoglycemic events play in patient health. "We have underestimated the risk from hypoglycemia as a cause of death," Dr. Markolf Hanefeld said in an interview at the annual meeting of the European Association for the Study of Diabetes.
"Hypoglycemia is very dangerous, and is also under-recognized and under-reported. Our results are another reason to avid glycemic excursions and hypoglycemia," he said.
Patients who may be especially at danger for arrhythmias triggered by poor glycemic control are those with a history of cardiovascular disease and on treatment that can produce hypoglycemia, such as a complex insulin regimen or a regimen that includes a sulfonylurea, said Dr. Hanefeld, professor and director of the Centre for Clinical Studies at Dresden (Germany) Technical University.
Dr. Hanefeld recommended that in addition to performing 1-day glucose monitoring on all patients who meet similar criteria, physicians should perform 24-hour ECG monitoring on patients with a prior major cardiovascular event, patients on a complex insulin regimen, and patients treated with a long-acting sulfonylurea.
"If you record their ECG [for a day or more,] that’s even better, but also very expensive," he said. "The three most dangerous complications of hypoglycemia are ventricular tachycardia, atrial fibrillation, and ischemic reactions. Ventricular tachycardia was our focus because it can lead to ventricular fibrillation and sudden death."
The patient’s treatment should then be tailored to improve their glycemic profile, and patients at higher risk for arrhythmias should be identified.
In addition to improved glycemic control with additional or alternative antidiabetic drugs, many patients like the ones studied could benefit from treatment with a beta-blocker to minimize the potential impact of a ventricular arrhythmia. But beta-blockers cannot be given to all patients with type 2 diabetes and a history of atherosclerotic cardiovascular disease, because some patients have bradycardia and would not tolerate a beta-blocker.
Dr. Hanefeld enrolled 30 consecutive patients with type 2 diabetes and documented atherosclerotic cardiovascular disease. Patients had a hemoglobin A1c of less than 9% and were on stable treatment with insulin, a sulfonylurea-like glyburide, or both. The investigators excluded patients on any other antidiabetic treatment, patients with preexisting arrhythmias, and patients on any antiarrhythmic drug except for a beta-blocker. Enrolled patients averaged 68 years old, their average hemoglobin A1c was 7.3%, and all but one was a man.
Each patient underwent 5 consecutive days of simultaneous continuous glucose monitoring and ECG recording. During this period, severe hypoglycemic events – defined as a blood glucose level less than 3.1 mmol/L – occurred in 23 patients, with a total of 35 episodes. The average time of each severe episode was 40 minutes.
Twenty-eight of 30 patients had ventricular extrasystoles (VESs), with an average of more than 3,600 during 5 days of ECG recording. Seventeen patients had couplets, 10 had triplets, and 5 had ventricular tachycardia.
Analysis showed a statistically significant increase in the rate of severe VESs in patients who had a mean amplitude of glycemic excursions of at least 4.02 mmol/L, Dr. Hanefeld and his colleagues reported. The highest rate by far of VES occurred in patients who had at least one severe hypoglycemic event and a mean amplitude of glycemic excursions of greater than 5.61 mmol/L.
Dr. Hanefeld said that he and his associates on the study had no disclosures.