Kids, Weight, and Health
Examining the links between youth obesity and pre-diabetes
Researcher: Michael Goran, PhD
Occupation: Associate Director, Institute for Health Promotion & Disease Prevention Research, University of Southern California
Focus: Obesity and type 2 diabetes in children
Funding:ADA Mentor-Based Postdoctoral Fellowship
Type 2 diabetes doesn't come out of nowhere. Imagine a cosmic card game where the deck includes diet and weight, genes and geography—even ethnicity. Some people are dealt a bad hand right from the beginning. Latinos, for example, have the highest risk of developing diabetes of any minority group in America: Epidemiologists estimate that half of the Latino children born in the year 2000 will develop diabetes at some point in their lives.
It's a mystery researchers are eager to figure out. Diabetes is extremely common among Latinos, and becoming more so all the time. In 2000, nearly three-quarters of Latino children between the ages of 12 and 19 were overweight or obese, more than double the number in the white population. "It's sociocultural, possibly genetic, definitely physiological and metabolic," says Michael Goran, PhD, a researcher at the University of Southern California's Department of Preventive Medicine in Los Angeles. "It varies tremendously between ethnic groups. Different ethnic groups are more insulin resistant than whites," even controlling for the differences in average weight between different groups.
Yet relatively little is known about why members of America's largest and fastest-growing minority group are so much more likely to be overweight and to develop diabetes than the rest of the population. For almost a decade, the ADA has supported Goran's research into the question by funding postdoctoral researchers who work with him on the problem of pediatric obesity. (For Goran, the focus on ethnicity is no accident: USC is located in east Los Angeles, which is 98 percent Latino.) Goran wanted to know if childhood obesity automatically led to pre-diabetes, a condition a step below full-blown type 2 diabetes that involves resistance to insulin and blood glucose levels somewhat higher than normal. A third factor doctors look at is the body's beta cells, which are responsible for producing insulin. In people with pre-diabetes, the beta cells struggle to secrete enough insulin to compensate for the body's growing resistance. Over time, all these factors can play a big role in the development of type 2 diabetes.
To look at the connections between childhood obesity and pre-diabetes, Goran has spent the past decade examining the way risk factors play out as Latino children grow up. In 2000, Goran recruited more than 200 kids between the ages of 8 and 13 from clinics near USC. Children selected for the study had to be Latino, overweight, and have a family history of type 2 diabetes. Every year, Goran's lab brought the kids in for a complete checkup, including a metabolic assessment that measured things like insulin sensitivity and glucose levels—both key indicators of pre-diabetes.
The kids in his study were selected because their weight was extreme, especially when measured against their peers. "Body weight in children is a moving target," Goran says. "In childhood we can't use a fixed body mass index, so we use a percentile." Most of the children were in the heaviest 3 percent for their age, topping 140 pounds at 10 years old, for example.
Goran's latest research, published in August in the journal Diabetes, analyzed the data from 128 of the children. What he found was surprising: Even though the kids in his study tended to keep gaining weight, the likelihood that they would show signs of pre-diabetes varied with each checkup. While half had signs of it sometimes, only 13 percent of them showed up with symptoms of pre-diabetes every year. "That shows the need for frequent screening," Goran says. "A one-time screening may not catch it."
Those same kids also built up fat in a different way than other children. Goran's team used an MRI scanner to look at where fat accumulated inside the body. The children with persistent signs of pre-diabetes tended to have more visceral fat, the kind that builds up deep inside the body to pad our organs, and less subcutaneous abdominal fat—the stuff that accumulates just under the surface. Says Goran: "Visceral fat is probably metabolically different." The difference could help explain why some people are more likely
to develop diabetes.
Goran has been following the kids in the study for almost a decade now. He and his team examine them each year. As they get older, he hopes to keep in touch and learn more about the connections between pre-diabetes, childhood obesity, and the development of type 2 diabetes later in life. "The kids in this cohort are going to get type 2 diabetes earlier," he predicts. By learning how, and why, he hopes to help provide strategies to stave off type 2 diabetes in one of America's most at-risk groups—and perhaps re-shuffle the type 2 deck.
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