Middle-School Based Primary Prevention Trial of Type 2 Diabetes (HEALTHY)

General Description

The HEALTHY study is a randomized prevention trial that investigated the effectiveness of an integrated intervention in middle schools that aimed to moderate risk for type 2 diabetes in children. The trial was conducted at 7 field centers in 42 middle schools, randomly assigned to intervention or control. Student recruitment and baseline data collection occurred during in the first semester of 6th grade (2006); the intervention was implemented the following semester (2007) and continued through 8th grade (2007-2009). For schools that received intervention, the program consisted of four integrated components targeting nutrition, physical education, behavior change initiatives, and educational communications activities that were designed to impact the environment and lifestyle choices of middle school children. The intervention was implemented either school-wide or grade-wide, so all students were exposed; those who provided appropriate informed consent participated in data collection and evaluation. The primary outcome measure was the combined prevalence of overweight and obesity (BMI ≥ 85th percentile). The study found that the combined prevalence of overweight and obesity decreased in both intervention and control schools, with no significant difference between school groups. However, the intervention did result in significantly greater reductions in various indexes of adiposity, including obesity.

Detailed information about the HEALTHY study, including the protocol, intervention materials, and publications, is available at www.healthystudy.org.

Objectives

The main goal of the HEALTHY study was to assess the effects of a school-based intervention program on risk factors for diabetes among middle-school aged children whose race/ethnicity and socioeconomic status placed them at high risk for obesity and type 2 diabetes. In addition to the primary objective of affecting risk for type 2 diabetes, major secondary objectives included further understanding and characterization of the etiology of risk of type 2 diabetes in this age group; evaluating the ability of the intervention to influence lifestyle changes and choices both in and out of school; determining the cost-effectiveness of the intervention; and comparing academic performance, attendance, and comportment in intervention versus control schools.

Outcome Measure

The primary outcome measure was the combined prevalence of overweight and obesity (BMI ≥ 85th percentile). Secondary outcome measures included prevalence of obesity (BMI ≥ 95th percentile), BMI z score, and continuous and categorical measurements of waist circumference, fasting glucose level, and fasting insulin level.

Criteria

Inclusion criteria for schools eligible to participate in the study included:

• A student body at least 50% minority and at least 50% eligible for free or reduced lunch
• Annual school-wide attrition from all causes ≤ 25%
• Expected cohort size of at end of study of at least 50 per school (determined by applying 50% anticipated enrollment rate and annual school-wide attrition rate over 3 years)

Students were eligible to participate if they met the following criteria:

• Ability to participate in the school’s standard PE program
• No diagnosis of diabetes
• Informed consent from both parent/guardian and student

Outcome

The combined prevalence of overweight and obesity decreased in both intervention and control schools, with no significant difference between school groups. However, intervention schools had greater reductions in various indexes of adiposity, including BMI z score, percentage of students with waist circumference at or above the 90th percentile, and fasting insulin levels. These changes may reduce the risk of childhood-onset type 2 diabetes.