Low Blood Sugar & Heartbeat in People With Diabetes
Study found abnormal rhythms when blood sugar dipped at night in people with type 2 disease
By Serena Gordon
TUESDAY, April 22, 2014 (HealthDay News) -- Low blood sugar levels -- known as hypoglycemia -- in people with diabetes may cause potentially dangerous changes in heart rate, according to a small new study.
This study's findings may help explain why a large-scale study found that very tight control of blood sugar levels in people with type 2 diabetes led to higher-than-expected death rates. It may also help explain why some otherwise healthy people with type 1 diabetes die during their sleep -- sometimes called "dead-in-bed syndrome" -- without an apparent cause, researchers say.
"We found that hypoglycemia was fairly common and that nocturnal episodes in particular were generally marked by a pattern whereby glucose levels dropped to low levels for some hours during which patients slept," said Dr. Simon Heller, senior study author and a professor of clinical diabetes and honorary consultant physician at the University of Sheffield, in England.
"These periods of hypoglycemia were associated with a high risk of marked slow heart rates [bradycardia] accompanied by [abnormal] beats. We have therefore identified a mechanism which might contribute to increased mortality in individuals with type 2 diabetes and high cardiovascular risk during intensive insulin therapy," Heller said.
Low blood sugar levels are not uncommon in people with diabetes, a disease that can produce dangerously high blood sugar levels. That's because the very treatments that can help prevent high blood sugar levels -- and the serious complications that accompany long-term high blood sugar levels -- can cause blood sugar levels to drop too low.
Although some oral diabetes medications can cause low blood sugar levels, the most common treatment to drop blood sugar levels too low is insulin. Insulin is a naturally occurring hormone that helps usher sugar into cells to be used as fuel.
"Your body needs fuel to survive and run properly," said Dr. Simon Fisher, an associate professor of medicine, cell biology and physiology at Washington University in St. Louis. "During hypoglycemia, the body is low on energy. When hypoglycemia is more severe, the brain [which runs on sugar] can get confused and stop functioning. If the blood sugar gets low enough, hypoglycemia can be fatal."
Fisher is also a co-author of an editorial accompanying the study in the May issue of Diabetes.
Low blood sugar is a well-recognized problem for people with type 1 diabetes, who must take multiple daily injections of insulin because their bodies no longer produce the hormone, according to study author Heller. But, low blood sugar generally isn't considered to be as significant a problem in type 2 diabetes, noted Heller, who added that the researchers were somewhat surprised to see that people with type 2 diabetes had low blood sugar levels about 10 percent of the time.