Obesity and Other Risk Factors for Youth Diabetes Improved by Broad, School-Based Intervention Program

June 29, 2010

June 29, 2010 (Orlando, Florida) — A broad-based program to fight obesity and diabetes, aimed at US middle-school students and conducted directly by their teachers and other local school officials and designed to profoundly change not only diet but also attitudes about food and fitness, appeared to improve measures of adiposity, insulin resistance, and other diabetes risk factors in a prospective randomized trial [1]. The findings were presented here yesterday at the American Diabetes Association (ADA) 2010 Scientific Sessions and published online June 27, 2010 in the New England Journal of Medicine.

However, there wasn't a significant difference between students at schools that ran the three-year program and control schools, where the program wasn't instituted, in the study's primary end point: change in the prevalence of kids who were overweight or obese, defined as a body-mass index (BMI) in the >85th percentile. The prevalence fell similarly at schools with and without the intervention program.

By 1999, some pediatric centers, especially those in inner cities, were seeing more new cases of type 2 diabetes than type 1.

The program, which followed the students from the beginning of sixth grade to the end of eighth grade, also did not show a significant benefit in lowering the overall prevalence of kids who were obese at its conclusion--that is, who finished the study in the >95th percentile for BMI. That prevalence fell by 19% at program compared with nonprogram schools, but the difference fell just short of significance at p=0.05.

However, the proportion of kids with waist circumference in the >90th percentile fell significantly more (p=0.04) at program schools. Students at those schools also had significantly (p=0.04) smaller increases in fasting insulin levels over the three years.

The program's benefits in the overall school populations were even more pronounced and more solidly significant among the approximately one-half of students in the >85th percentile for BMI at the beginning of sixth grade.

Dr Gary D Foster

"This would suggest that, although the intervention did not meet its primary outcome of altering the combined prevalence of overweight or obesity, it did have effects on obesity and other important risk factors for type 2 diabetes, Dr Gary D Foster (Temple University, Philadelphia, PA) said at a briefing for medical reporters. Foster chaired the HEALTHY study--a name, not an acronym, chosen by students who participated in the comprehensive program.

He also said that the falling overweight/obesity rates at schools with and without the intervention program are consistent with national-level trends observed in other analyses that suggest that "rates of obesity in high-risk children in sixth to eighth grade appear not to be steady or increasing but actually appear to be declining."

The HEALTHY study randomized 42 schools in seven regions of the US to follow or not follow the comprehensive intervention program. Schools qualified for participation if at least 50% of their students were members of a minority (primarily Hispanic or African American) or at least 50% qualified for government-subsidized meal programs; minority and low-income kids, the researchers note, are known to be at increased risk for both obesity and diabetes. Girls made up 53% of the 4603 students tracked in the study, who had to be free of recognized diabetes at baseline.

Dr Griffin P Rodgers

At the press briefing, Dr Griffin P Rodgers (National Institutes of Health, Bethesda, MD), who is director of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the HEALTHY study's primary underwriter, but who isn't one of its investigators, underscored the importance of targeting kids at increased risk for diabetes. "Earlier onset of diabetes may foreshadow earlier appearance of complications," he noted.

When the HEALTHY study and its six preceding pilot studies were initially in development, he continued, "obesity rates in American youth had been climbing steadily for two decades. Then, medical centers around the country began reporting a disturbing new trend: type 2 diabetes was increasingly being diagnosed in youths, especially black, Hispanic, and American Indian adolescents. By 1999, some pediatric centers, especially those in inner cities, were seeing more new cases of type 2 diabetes than type 1. We needed to find ways to contain the rising rate of type 2 diabetes in kids, and schools were a logical place to start."

Dr Cynthia L Ogden

Dr Cynthia L Ogden (Centers for Disease Control and Prevention [CDC], Atlanta, GA), also on hand at the briefing but not a HEALTHY study researcher, showed 2007–2008 data from the National Health and Nutrition Examination Survey suggesting that 31.7% of US children aged two to 19 are overweight or obese, amounting to 23.4 million children. Among them, she said, are the 17% of US kids in that age group, a total of about 12.5 million, who qualify as obese.

Dr Kathryn Hirst

Also, Rodgers said, the HEALTHY pilot trials suggested that up to 40% of eighth graders at schools with high-risk populations had elevated fasting glucose levels. "So the question became, can changes in schools--namely, longer and more intense gym classes, healthier food choices, and classroom activities that promote healthy behavior--lower risk factors for type 2 diabetes in youth?"

Dr Kathryn Hirst (George Washington University School of Public Health, Washington, DC) provided more details of the intervention program, which consisted of "multiple components that were designed to change the school environment radically." Experts on the study's staff at its seven regional field offices provided "training, guidance, assistance, materials, and support" for instituting the program to the faculties and staff at each of the schools--"who were the ones who actually delivered the intervention," she noted.

Overall Change From Baseline to End of Study Perioda in Diabetes Risk Markers in the HEALTHY Study

Parameter

Control schools

Intervention schools

OR (95% CI)

p

Prevalence BMI >85th percentile (% units)

-4.1

-4.5

0.99 (0.82-1.19)

0.92

Prevalence BMI >95th percentile (% units)

-3.8

-5.5

0.81 (0.66-1.00)

0.05

Waist circumference >90th percentile (% units)

-5.9

-8.1

0.80 (0.64-0.99)

0.04

Fasting insulin level (U/mL)b

+4.0

+3.8

--

0.04

a. beginning of sixth grade to end of eighth grade

b. odd ratios not calculated for continuous variables

The program consisted of interventions grouped in four domains (details and the materials used are available on the study's website). The nutritional component called for healthy improvements in the quality and quantity of food and beverages available at the schools' cafeterias, snack bars, and vending machines and even at fund raisers and classroom parties, according to Hirst. Available choices shifted to those lower in fat, higher in fiber, heavier on fruit and vegetables, and lower in added sugar.

The physical-activity component was aimed at increasing both participation and activity levels in physical-education classes, emphasizing activities that raised the heart rate to at least 130 beats per minute, according to the published report of the HEALTHY study. Teachers received instruction on holding schoolwide events that promoted physical activity. Minimum weekly durations of physical-education classes were instituted.

The third component, focused on behavior, according to the report, promoted classroom and family-outreach activities to educate and sharpen self-awareness and decision-making, self-monitoring, and goal-setting skills consistent with the overall program.

The fourth component, communication, focused on the use of marketing techniques to promote the program's goals within the schools and establish a "brand" to characterize and identify the changes to menus and physical activities that were part of the program.

Change From Baseline to End of Study Perioda in Diabetes Risk Markers, Subgroup of the HEALTHY Study With Baseline BMI in the >85th Percentile

Parameter

Control schools

Intervention schools

OR (95% CI)

p

Prevalence BMI >85th percentile (% units)

-15.9

-16.5

0.96 (0.76-1.21)

0.72

Prevalence BMI >95th percentile (% units)

-8.5

-11.5

0.79 (0.63-0.98)

0.04

Waist circumference >90th percentile (% units)

-12.6

-17.0

0.78 (0.63-0.97)

0.03

Fasting insulin level (U/mL)b

+4.1

+3.6

--

0.04

a. beginning of sixth grade to end of eighth grade

b. odd ratios not calculated for continuous variables

Dr Marsha D Marcus

In her presentation of secondary results from the study, Dr Marsha D Marcus (University of Pittsburgh, PA) observed that program and nonprogram schools didn't differ significantly in their students' changes in total cholesterol, HDL cholesterol, triglyceride levels, blood-pressure changes, or the proportion of students with elevated glucose levels.

An exploratory subset analysis, she said, suggested that African American and white male students who had hypertension or prehypertension at baseline at program schools, compared with nonprogram schools, showed significant decreases in blood pressure.

"The HEALTHY study did not show a reduction in cardiovascular risk-factor rates, except for the change in blood pressure in black and white males, nor did it show improvements in fitness," Marcus said. "The robust HEALTHY intervention did reduce measures of obesity, which places middle-school students at great risk. On a public-health scale, even small rates of change can have dramatic population-wide implications."

Dr Philip S Zeitler

After the HEALTHY study was formally presented, childhood obesity expert Dr Philip S Zeitler (University of Colorado, Denver), an invited discussant, described the clinical context of and the basis for optimism over the trial's findings. "The average age of diagnosis of diabetes among youths is about 13.5 years for girls and 14.5 years for boys. So it appears that late in puberty, children will present with diabetes." Other data suggest that if children pass that age without a diabetes diagnosis, he said, they may not be at elevated risk again until later in adulthood.

"So there's something about that period in time, prior to age 13 or 14, that appears to be important for the development of youth diabetes. This is exactly the age at which the HEALTHY intervention was undertaken." During this high-risk period of life, according to Zeitler, the strongest predictors of type 2 diabetes are weight gain, particularly from increased visceral fat, and worsening insulin resistance.

Indeed, he noted, the HEALTHY study's intervention led to improvements in the amount of visceral fat, "as evidenced by waist circumference," and in fasting insulin in the absence of a change in glucose, "which suggests improvement in insulin sensitivity." And it occurred at a time in the children's lives when they were especially likely to have worsening insulin sensitivity.

The HEALTHY study was primarily funded by the NIDDK and the ADA. A list of corporations and individuals "who provided donations in support of the study's efforts" appears in the report. Disclosures for the investigators are available at www.nejm.org . Zeitler discloses consulting for AstraZeneca, Bristol-Myers Squibb, Daiichi Sankyo, and Merck-Schering Plough, and receiving research support from Eli Lilly. Ogden said she has no conflict-of-interest disclosures and that her statements represent her own opinions, independent of the CDC.

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