August 2008 - A study by researchers at the University of Southern California (USC) found that overweight Hispanic children are at significant risk for pre-diabetes, a condition marked by higher than normal blood glucose levels that are not yet high enough for a diagnosis of diabetes. The persistence of pre-diabetes during growth is associated with progression in risk towards future diabetes, according to the study, which will be published in an upcoming issue of the journal Diabetes, and is now available online.
With a population of more than 35 million, Hispanics are the largest and fastest growing minority group in the United States. Despite the fact that Hispanics are at high risk for developing type 2 diabetes, few previous studies have looked at physiological causes of the disease within this population.
Researchers led by Michael I. Goran, Ph.D., professor of preventive medicine, physiology and biophysics and pediatrics, and director of the USC Childhood Obesity Research Center at the Keck School of Medicine of USC, followed a cohort of 128 overweight Hispanic children in East Los Angeles. The children were tested over four consecutive years for glucose tolerance, body mass index, total body fat and lean mass and other risk factors for type 2 diabetes. The study found that an alarming 13% of the children had what the investigators termed "persistent pre-diabetes."
Most prior studies examining pre-diabetes in overweight and obese children looked at a one-time assessment of metabolic risk factors for type 2 diabetes, but fluctuations over time led to poor reliability for these tests. In the new study, Goran and colleagues examined longitudinal data to look at a progression of risk factors over four years. Children were identified as having persistent pre-diabetes if they had three to four positive tests over four annual visits. The children who had persistent pre-diabetes had signs of compromised beta-cell function, meaning that their bodies were unable to fully compensate to maintain blood glucose at an appropriate level, and they had increasing accumulation of visceral fat or deposition of fat around the organs. Both of these outcomes point towards progression in risk towards type 2 diabetes.
"What this study shows is that doctors should be doing regular monitoring of these children over time, because a one-time checkup might not be enough to tell if they are at risk for developing diabetes," Goran says.
Visceral fat, which pads the spaces between abdominal organs, has been linked to metabolic disturbances and increased risk for cardiovascular disease and type 2 diabetes.
Increased obesity has been identified as a major determinant of insulin resistance. Lower beta-cell function is a key component in the development of type 2 diabetes, as the cells are unable to produce enough insulin to adequately compensate for the insulin resistance.
"To better treat at-risk children we need better ways to monitor beta-cell function and visceral fat buildup," Goran says. "Those are tough to measure but are probably the main factors determining who will get type 2 diabetes."
Future studies will examine different interventions, including improving beta-cell function and reducing visceral fat.
"The study provides great insight into the risk factors that lead to the progression towards type 2 diabetes in this population," says Francine Kaufman, professor of pediatrics at the Keck School of Medicine at USC and head of the division of endocrinology and metabolism at Childrens Hospital Los Angeles, who was not directly involved in the study. "Only by understanding how this devastating disease develops will be able to begin taking steps to prevent it."
The study was supported by the National Institutes of Health and the General Clinical Research Center, National Center for Research Resources.
Michael I. Goran, Christianne Lane, Claudia Toledo-Corral and Marc J. Weigensberg. "Persistence of Pre-Diabetes in Overweight and Obese Hispanic Children: Association With Progressive Insulin Resistance, Poor Beta-cell Function and Increasing Visceral Fat."Diabetes. DB-08-0445
Source: University of Southern California Health Sciences