A common treatment for children in diabetic crisis apparently contributes to a rare -- but often fatal -- complication known as cerebral edema, according to a study by researchers at University of California-Davis School of Medicine and Medical Center.

The study, the largest and most statistically rigorous examination yet of risk factors for cerebral edema in children with diabetic ketoacidosis, was published in the Jan. 25, 2001 issue of the New England Journal of Medicine.

Researchers found that bicarbonate, a common treatment for diabetic ketoacidosis, appears to increase the risk of cerebral edema, or swelling of the brain, which can be fatal. In ketoacidosis, toxic levels of acids called ketones build up in the blood. Bicarbonate is often given in the emergency department to reduce these acid levels.

"In the past there has been some suspicion that giving bicarbonate can increase risk of cerebral edema, but ours is the first study to show that it can," said Nathan Kuppermann, senior author of the study, a pediatric emergency physician and associate professor of internal medicine at UC- Davis.

Cerebral edema can lead to coma, neurological damage, and death. While the complication occurs in only about one percent of diabetic ketoacidosis cases in children, 40-90% of children who develop cerebral edema die, and many others are left with permanent brain damage. In all, cerebral edema accounts for 50-60% of diabetes-related deaths in children.

The results were so clear that the authors concluded: "Treatment with bicarbonate is associated with increased risk of cerebral edema and should be avoided in most circumstances."

Caused by too little insulin in the body, diabetic ketoacidosis occurs mainly in patients with Type I diabetes mellitus, also known as juvenile diabetes or insulin-dependent diabetes. Symptoms of ketoacidosis include unusual thirst, frequent urination, constant fatigue, dry or flushed skin, nausea and vomiting, labored breathing, confusion, and a fruity odor on the breath. The condition requires immediate emergency medical intervention.

For up to 40% of children with new-onset Type I diabetes, ketoacidosis is the first recognized sign of disease. Ketoacidosis also can occur later in the course of the disease if a diabetic patient misses an insulin injection, gets sick or is subjected to some other significant stress.

Kristi Oppold, of Woodland, Calif., is among the 25-40% of children who first found out she had diabetes when she developed ketoacidosis. She is also one of the rare children to develop cerebral edema. Fortunately, she survived without any permanent neurological damage.

"It is the scariest thing I've ever experienced," Terri Oppold says of her daughter's 12-hour coma, brought on by the brain swelling. "No child should have to go through this."

In their study, Dr. Nicole Glaser -- pediatric endocrinologist and assistant professor of pediatrics at UC-Davis -- and her colleagues reviewed the medical charts of 6,977 children hospitalized for diabetic ketoacidosis over a 15-year period at 10 medical centers. These children were compared with two control groups of children with diabetic ketoacidosis who did not develop cerebral edema. Comparisons among the groups were subjected to a series of sophisticated statistical tests.

Other studies have attempted to identify risk factors for cerebral edema in children with diabetic ketoacidosis. However, the studies were small, lacked control groups for comparison, and reached contradictory findings.

Each year 30,000 Americans are diagnosed with Type I diabetes, more than 13,000 of them children, according to the Juvenile Diabetes Foundation. In Type I diabetes, the pancreas produces little or no insulin.

SOURCES: "Risk Factors for Cerebral Edema in Children with Diabetic Ketoacidosis,"

Nicole Glaser. New England Journal of Medicine, Jan. 25, 2001.