Corrected QT Interval Prolongation during Severe Hypoglycemia without Hypokalemia in Patients with Type 2 Diabetes

Abstract

BackgroundTo evaluate the effects of severe hypoglycemia without hypokalemia on the electrocardiogram in patients with type 2 diabetes in real-life conditions.MethodsElectrocardiograms of adult type 2 diabetic patients during the episodes of severe hypoglycemia and the recovered stage were obtained and analysed between October 1, 2011 and May 31, 2012. Patients who maintained the normal serum sodium and potassium levels during the episodes of severe hypoglycemia were only selected as the subjects of this study. Severe hypoglycemia was defined, in this study, as the condition requiring active medical assistance such as administering carbohydrate when serum glucose level was less than 60 mg/dL.ResultsNine type 2 diabetes patients (seven men, two women) were included in the study. The mean subject age was 73.2±7.7 years. The mean hemoglobin A1c level was 6.07%±1.19%. The median duration of diabetes was 10 years (range, 3.5 to 30 years). Corrected QT (QTc) intervals were significantly increased during the episodes of severe hypoglycemia compared to the recovered stage (447.6±18.2 ms vs. 417.2±30.6 ms; P<0.05). However, the morphology and the amplitude of the T waves were not changed and ST-segment elevation and/or depression were not found during the episodes of severe hypoglycemia.ConclusionIn this study, QTc interval prolongation during the episodes of severe hypoglycemia was observed without hypokalemia. Therefore, the distinct alterations in cardiac repolarization during the episodes of severe hypoglycemia may not be associated with hypokalemia.

Blood electrolyte disturbances during severe hypoglycemia in Korean patients with type 2 diabetes

“…It is well accepted that the prolongation of QTc intervals related to ventricular arrhythmias and sudden death is induced by severe hypoglycemia in patients with both type 1 and type 2 diabetes [ 20 ]. Although hypoglycemia itself without hypokalemia might cause the prolongation of QTc interval in patients with type 2 diabetes [ 21 ], hypoglycemia with hypokalemia could augment the prolongation of the QTc interval [ 6 , 20 ]. Moreover, hypokalemia-associated with hypoglycemia is known to be associated with hyperinsulinemia and the increased secretion of catecholamines [ 20 , 22 ].…”

Avoiding or coping with severe hypoglycemia in patients with type 2 diabetes

“…In the ADVANCE and ACCORD trials, severe hypoglycemia was associated with a significantly increased risk of major cardiovascular events and a 1.4 to 3-fold higher risk of mortality [ 6 , 48 ]. Hypoglycemia changed cardiac repolarization and induced arrhythmias in patients with type 1 and type 2 diabetes [ 49 , 50 , 51 ]. The previously reported EURODIAB IDDM complication study demonstrated that severe hypoglycemia events were independently associated with a prolonged corrected QT (QTc) interval in type 1 diabetic patients [ 52 ].…”

“…A prolonged QTc interval reflects abnormalities in ventricular myocardial repolarization, and is an independent risk factor for mortality in patients with type 1 diabetes [ 53 ]. Similarly, myocardial ischemic changes with a prolonged QT interval have been also observed during insulin-induced hypoglycemia in patients with type 2 diabetes [ 49 , 50 , 54 ].…”

Update on strategies limiting iatrogenic hypoglycemia

“…Hypoglycemia might affect cardiac repolarization (48) and leads to EKG changes, including altered ST-segment and T-wave morphology and QT interval prolongation (49) . The latter is thought to be a possible mechanism leading to fatality during CV events, being precipitated by increased circulating levels of cathecolamines and hypokalemia (50, 51) , even if hypokalemia does not always play an important role during severe hypoglycemia (52) . However, hypoglycemia at admission was associated with increased 30-day mortality in acute myocardial infarction patients with or without T2DM (53) .…”