Why severe hypoglycemia can lead to arrhythmia and death….
In a study of patients with diabetes and severe hypoglycemia, hypertension, QT prolongation, and hypokalemia were fairly common, and this might explain why hypoglycemia can lead to fatal arrhythmia and death, researchers report.
Severe hypoglycemia was defined as requiring an emergency trip to the hospital by ambulance. Half of the patients with severe hypoglycemia and type 1 diabetes and more than half of those with type 2 diabetes had QT prolongation on their ECG readings, which might predict potential cardiac arrest, cardiovascular events, and subsequent death, reported senior author Dr. Mitsuhiko Noda (National Center for Global Health and Medicine, Tokyo, Japan).
Compared with patients with type 2 diabetes, those with type 1 diabetes were less likely to have severe hypertension, but they were just as likely to have the risk factors of hypokalemia and QT prolongation.
Cardiovascular disease, possibly caused by severe hypoglycemia, is thought to be the cause of excessive mortality observed among diabetic patients in the intervention arm of the recent large-scale trial (Action to Control Cardiovascular Risk in Diabetes) ACCORD.
The researchers performed a retrospective cohort study of all 414 cases (356 patients) of diabetes and severe hypoglycemia seen at their emergency department between January 2006 and April 2012. There were 326 cases of type 2 diabetes and 88 cases of type 1 diabetes; about 31% of the cases were women.
Patients with type 2 diabetes were older (mean age 71.4) than those with type 1 diabetes (mean age 44.6); they were also more likely to have a history of cardiovascular disease (MI, angina pectoris, or stroke): 22.1% vs 6.8%.
The researchers reviewed the records of the patients’ vital signs (body temperature, blood pressure, and heart rate) and ECGs, as well as other data from when the patients arrived at the hospital.
The two patient groups had a relatively high prevalence of conditions that increase the risk of lethal arrhythmia: prolonged QT interval, hypokalemia, and severe hypertension.
Several reasons might explain the differences between patients with severe hypoglycemia and type 2 diabetes vs type 1 diabetes, according to the investigators. "Type 1 diabetic patients typically have fewer comorbidities (such as hypertension and dyslipidemia) and have a weaker counterregulatory response to hypoglycemia . . . [as a result of] frequent episodes of hypoglycemia," they suggest.
Published online August 12, 2013 in Diabetes Care.