NEWS | June 18, 2008

Ketones may be culprits in some diabetics' heart problems

Cardiac monitoring of patients with diabetic ketoacidosis important to prevent rare, fatal events


A new study by researchers at UC Davis suggests that the rare but potentially life-threatening irregular heartbeat that sometimes occurs in children with diabetes may be caused by high levels of ketones in the blood that are the byproduct of the body burning its own fat stores for energy instead of food.

The study is published in the June issue of the Archives of Pediatric & Adolescent Medicine. The cardiac arrythmias in patients with diabetic ketoacidosis have been blamed on an imbalance of electrolytes, the ion-charged minerals that help the body's muscles, including the heart, maintain their electrical balance.

The investigators found frequent abnormalities on the electrocardiograms (EKGs) of children with diabetic ketoacidosis, which have the potential to lead to serious, life-threatening cardiac arrythmias.

But the study participants were found to have few irregularities in their electrolyte balance to account for the abnormalities.

"These findings suggest, first, that children and adults with diabetic ketoacidosis need to have careful cardiac monitoring," said lead study author and professor of pediatrics and emergency medicine Nathan Kuppermann. "Those recommendations are already in place by national and international endocrinology organizations."

Ketoacidosis occurs when the body is forced to break down its fat stores for energy. The breakdown of fat releases ketones into the blood, making it more acidic.

The researchers said that the study findings also have implications for others with ketoacidosis, including people on very-low-calorie, very-low-carbohydrate diets and alcoholics who experience the condition because they don't eat enough.

Though rare, cardiac arrythmias have been documented in adults and adolescents adhering to very-low-calorie, carbohydrate-restricted diets for weight loss.

"These patients typically have no known electrolyte abnormalities to account for this and sudden death has been attributed to myocardial atrophy caused by protein and micronutrient deficiencies and other causes," said Kuppermann, who also is the chairman of the UC Davis Department of Emergency Medicine.

"We don't want to be alarmist, but this study suggests that delayed cardiac re-polarization due to ketosis leading to serious cardiac arrhythmias may be a cause of death in some of these cases," he said.

The study examined 30 children with type-1 diabetes and diabetic ketoacidosis. Each received two EKGs, one at the start of treatment and a second at the conclusion of treatment. Treatment for all of the patients was successful and their diabetic ketoacidosis resolved without complications.

The researchers found that nearly half — 47 percent — of the electrocardiograms showed an abnormality associated with cardiac arrhythmias, called a prolonged Q-T interval. The prolonged Q-T interval describes a time interval between waveforms on the EKG tracing that if prolonged may be associated with a potentially life-threatening arrhythmia — called torsade de pointes — that causes rapid, uncoordinated contractions that prevent the heart's chambers from adequately refilling and pumping oxygen-rich blood to the body.

Electrolyte imbalances in the body may also lead to cardiac arrythmias in these patients. However, there were no significant problems with electrolyte balance in the study patients, leading researchers to conclude that the ketosis was the primary cause of the prolonged Q-T intervals.

The study concludes that current consensus statements recommending continuous cardiac monitoring of children with diabetic ketoacidosis should be strictly followed.

"Although it is not certain that the rare fatal events during DKA are caused by (Q-T prolongation), our findings suggest that cardiac monitoring of children with diabetic ketoacidosis is important, and investigation of (Q-T prolongation) in other ketotic conditions should be considered," Kuppermann said.

Funding for the study was provided by an American Diabetes Association Clinical Research Award and a UC Davis, Health System Award. Other study authors include Jeanny Park, Kathryn Glatter, James Marcin, and Nicole Glaser, all of UC Davis.

UC Davis Health System is an integrated, academic health system encompassing UC Davis School of Medicine, the 577-bed acute-care hospital and clinical services of UC Davis Medical Center, the 800-member physician group known as UC Davis Medical Group, and the proposed Betty Irene Moore School of Nursing.