Middle-School Based Primary Prevention Trial of Type 2 Diabetes

In response to increases in incident cases of type 2 diabetes in American children and youth, NIDDK funded a multi-site primary prevention trial designed to moderate risk for type 2 diabetes in middle school aged children. In pilot studies, it was found that an indicator of adiposity, a body mass index greater than the 85th percentile for gender and age, was the most prevalent, modifiable risk factor for diabetes in this age group. In addition, indicators of insulin resistance and dysglycemia, elevated mean fasting insulin and glucose levels, were assessed to determine if the intervention was capable of reducing these risk factors for diabetes in middle school aged children.

The trial was conducted at 7 field centers in 42 middle schools randomly assigned to intervention or control. Following student recruitment and baseline data collection in the first semester of 6th grade (2006), the intervention was implemented in the second semester of 6th grade (2007) and continued throughout 7th (school year 2007-2008) and 8th (school year 2008-2009) grades. All students were exposed to components of the intervention, which were implemented school-wide or grade-wide; however, only students who provided appropriate informed consent and assent participated in data collection and evaluation. The primary objective of the trial was to determine if, at the end of the 8th grade, the intervention significantly impacted the risk for developing type 2 diabetes compared to control.

Six pilot studies were performed to collect data to guide the development of an intervention. The prior studies focused on:

• Establishing the feasibility of recruiting students and obtaining physical and physiological measurements, including fasting and 2-hour post glucose load blood draws (early 2003).
• Evaluating a physical education (PE) class program designed to increase moderate-to-vigorous physical activity (late 2003).
• Testing the ability of a nutrition intervention to change food and beverage offerings in school food service and vending (early 2004).
• Implementing a program that integrated the PE class and food service nutrition interventions with a communications and awareness campaign (fall 2004).
• Determining the feasibility of a behavior change intervention, delivered through in-class and other school settings and family outreach, to accomplish self monitoring and goal setting (fall 2005).
• Evaluating PE class activities targeting 7th and 8th graders and a training and support program to motivate PE teacher buy-in and adherence (fall 2005).

Formative research was conducted to inform the creation of all intervention components.

Based on a comprehensive review of the literature and the pilot study results, a robust multi-component intervention was developed to impact the environment and lifestyle choices of middle school children. The intervention consisted of the following integrated components:

• changes in the nutritional quality of food and beverage offerings throughout the total school food environment, including cafeteria meals and programs, a la carte, and vending machines;
• changes in the physical education (PE) program, equipment, and teacher training to increase both participation and number of minutes spent in moderate-to-vigorous physical activity when implemented by PE teachers in PE class;
• brief classroom activities designed to increase knowledge, enhance decision making skills, promote peer involvement and interaction, and enhance social influence;
• individual and group behavior change initiatives aimed at promoting healthier behaviors through self monitoring, goal setting, and problem solving;
• family outreach to involve parents/guardians and family members by providing information and strategies to support youth in accomplishing behavioral goals; and
• school-wide communications to enhance and promote changes in nutrition, activity, and behavior.

In addition to the primary objective of affecting risk for T2D, major secondary objectives were to: further understand and characterize the etiology of risk of T2D in this age group; evaluate the ability of the intervention to influence lifestyle changes and choices both in and out of school; determine the cost-effectiveness of the intervention; compare academic performance, attendance, and comportment in intervention versus control schools; and describe the influence of non-study changes in the school environment that affect student nutrition and physical activity. Finally, data were collected to evaluate the degree to which the components of the intervention were delivered and administered as planned.

Inclusion criteria

• Middle school student body is at least 50% minority (defined as African American, Hispanic/Latino, and/or Native American) and/or greater than 50% eligible for free or reduced lunch.
• Middle school annual school-wide attrition from all causes is <= 25% (estimate determined from data provided by the school).
• Middle school expected cohort size at end of study is at least 50 per school determined by applying 50% anticipated enrollment rate and annual school-wide attrition rate over 3 years.
• Student able to participate in the school's standard PE program.
• Student's parent/guardian has provided informed consent for the child to participate in data collection and evaluation procedures.
• Student has provided informed assent to participate in data collection and evaluation procedures.

Exclusion criteria

(none specified)