Relationship Between Hypoglycemic Episodes and Ventricular Arrhythmias in Patients With Type 2 Diabetes and Cardiovascular Diseases: Silent Hypoglycemias and Silent Arrhythmias

OBJECTIVE In patients with type 2 diabetes and cardiovascular diseases (CVDs), intensive treatment with insulin and/or sulfonylurea (SU) may be associated with excessive increased risk of hypoglycemic episodes. To evaluate the risk of critical arrhythmias related to glycemic variability, we carried out an observational study in type 2 diabetes patients with CVD. RESEARCH DESIGN AND METHODS Thirty patients with type 2 diabetes and documented CVD who had been treated with insulin and/or SU underwent 5 days of monitoring with a continuous glucose measurement system along with parallel electrocardiogram recording for monitoring of ventricular arrhythmias. Twelve age-matched patients with documented CVD who received treatment with metformin and/or dipeptidyl peptidase-4 inhibitor served as the control group. Patients were receiving stable treatment, and were instructed to notice symptoms of arrhythmias and hypoglycemia, respectively. RESULTS We observed a high incidence of asymptomatic severe episodes of hypoglycemia (<3.1 mmol/L) in patients receiving treatment with insulin and/or SU, whereas severe hypoglycemia did not develop in any of the control subjects. Patients with severe hypoglycemia (n=12) had a higher number of severe ventricular arrhythmias (patients with versus without severe hypoglycemia, respectively: ventricular couplets 41.7 ± 81.8 vs. 5.5 ± 16.7; ventricular tachycardia 1.0 ± 1.9 vs. 0.1 ± 0.3). No direct correlation could be found among different variables of glucose profile, corrected QT interval, and ventricular arrhythmias. CONCLUSIONS Our results suggest that severe episodes of hypoglycemia are associated with an increased risk of severe ventricular arrhythmias.