Reducing insulin resistance and boosting the fitness of overweight Latino children at high risk for type 2 diabetes will be crucial in efforts to protect them from diabetes and heart disease, according to investigators from the Keck School of Medicine.
The USC research team, which is conducting expansive studies on the patterns of metabolic change among Latino children and teens, presented initial results from their investigations at the 2003 Annual Meeting of the North American Association for the Study of Obesity, or NAASO, held in mid-October in Fort Lauderdale, Fla.
The team’s findings highlight a weighty quandary for the nation: How to help Latino children who are being hit especially hard by a vicious circle of obesity, insulin resistance, metabolic challenges as well as heightened disease risk.
“Obesity is now a critical, common nutritional problem in children,” said Michael I. Goran, professor of preventive medicine and physiology and biophysics at the Keck School and study presenter. “It disproportionately affects minority groups and is the major contributor to the recent emergence of type 2 diabetes among children. We need to do something now to understand and prevent these chronic diseases.”
Reports have recently drawn attention to the nation’s mounting problem of expanding waistlines. The latest estimates suggest that nearly a third of African-American and Latino kids are overweight; many are being diagnosed with type 2 diabetes—once exclusively an adult disease—during puberty.
Type 2 diabetes is a metabolic problem that results when the body cannot make enough insulin or its cells become resistant to insulin. Insulin is a hormone the body uses to bring glucose, or sugar, from the blood into tissues to be used as an energy source.
Keck School researchers wanted to better understand causes of metabolic problems among Latino children. Latinos are twice as likely as non-Latino whites to develop diabetes. With funding from the National Institutes of Health, the researchers are studying more than 200 healthy Latino children ages 8 to 13 in Los Angeles.
Among the findings presented at NAASO:
• Nine of every 10 overweight Latino children had at least one risk factor for cardiovascular disease and type 2 diabetes. This appears to be due to low sensitivity to insulin.
• Three of every 10 kids had three or more features of the metabolic syndrome: obesity around the belly, low levels of HDL cholesterol (“good cholesterol”), high triglycerides and high blood pressure.
• Higher insulin sensitivity was tied to higher HDL, and lower insulin sensitivity was linked to higher tryglyceride levels and blood pressure. Since these are risk factors for cardiovascular disease and type 2 diabetes, researchers suggest that increasing insulin sensitivity is crucial for preventing chronic disease in childhood.
Overweight Latino children with the metabolic syndrome were much less physically fit than kids with no metabolic syndrome features—regardless of body composition or sensitivity to insulin. Researchers measured cardiovascular fitness by logging each child’s VO2max (the volume of oxygen their bodies could use while exercising full-tilt) and found that the greater their VO2max, the lower the kids’ blood pressure.
They also found that kids with three or more features of the metabolic syndrome had much lower VO2max than kids with no features of the metabolic syndrome. Metabolic syndrome strongly predicts both cardiovascular disease and type 2 diabetes, so researchers believe that improving fitness would be a worthy way of deterring these diseases among such children.
About 28 percent of heavy Latino children with a family history of type 2 diabetes already have pre-diabetes—elevated blood sugar levels—linked to beta cells that have started to fail. Overweight kids who had elevated blood sugar levels, or impaired glucose tolerance, had poor beta-cell function that deteriorated with age.
Beta cells are special cells in the pancreas that create insulin. Impaired glucose tolerance was especially common among children whose mothers developed type 2 diabetes during pregnancy, also called gestational diabetes.
“We knew this was a high-risk population, but the extent of these risk factors and the magnitude of the health problems was bigger than we expected,” said Goran, associate director of the USC Institute for Prevention Research. “These overweight children are effectively walking time-bombs, and the metabolic basis of these risk factors must be targeted in interventions.”
Besides Goran, researchers involved in associated studies included Richard N. Bergman, Quintila Avilla, Michael Watkins, Geoff Ball, Gabriel Q. Shaibi, Marc J. Weigensberg, Martha L. Cruz, George Salem and Hassan A. Kobaissi.
“Obesity, Insulin Resistance and the Metabolic Syndrome in Overweight Hispanic Children,” part of the Childhood Obesity: Obesity/Diabetes Relationships symposium, 2003 Annual Meeting of the North American Association for the Study of Obesity. For further information on the NAASO meeting, visit www.naaso.