Low Glycemic Load Diets in Latino Children at Risk for Type 2 Diabetes
Condition: Obesity; Type 2 Diabetes Mellitus
MeSH terms: Diabetes Mellitus; Diabetes Mellitus, Type 2
Study type: Interventional
Phase: Phase 2/Phase 3

Summary: 
      The purpose of this study are to:

        1. compare two diet plans - a low-glycemic load (low-GL) diet and a low-fat diet. A low-GL
           diet is expected to keep blood sugar levels more normal, and because the sugar levels
           stay normal, prevent rapid rises of insulin in the blood. We want to test if Hispanic
           children at-risk for type 2 diabetes who are given a low-GL diet will have less insulin
           resistance, will lose more weight, and will decrease their chance of getting type 2
           diabetes.

        2. compare the effects of Low-GL and high-GL meals on appetitive, hormonal, and metabolic
           responses of obese Hispanic youth under controlled, standardized conditions. We want to
           test if children fed low-GL meals would have lower glucose and lower insulin responses,
           report less hunger and consume less energy than those fed high-GL meals.
    

Detailed description: 
      Overweight among minority children and adolescents is now the most prevalent pediatric public
      health problem in the United States. Our preliminary studies have found the prevalence of
      overweight among Hispanic children and adolescents in Washington DC is more than twice the
      U.S. national average. It is well established that overweight is associated with both medical
      and psychosocial complications, particularly for minority populations. Study of overweight
      Hispanic children has shown that they are at high risk for insulin resistance and impaired
      glucose tolerance (IGT), with IGT present in 28% of overweight Latino children with a family
      history of type 2 diabetes (T2DM). Despite the urgency to develop effective strategies to
      treat obesity and prevent T2DM in such children, few randomized controlled trials of weight
      management have been conducted in Hispanic children. Hence, there is an urgent need to
      develop effective, feasible and culturally competent obesity treatment programs targeted to
      Hispanic youth who are at great risk for obesity-associated co-morbidities, and who represent
      the fastest growing segment of the U.S. population.

      A low-glycemic index (GI) or glycemic load (GL) diet is a much discussed, but quite
      controversial treatment of obesity. Some, but not all epidemiological studies show lower risk
      of diabetes among individuals consuming a low-GL diet. Short-term clinical studies examining
      the hormonal and biochemical responses to a low-GI diet have documented a reduction of
      reactive hyperglycemia and hyperinsulinemia, and decrease food intake. We propose that a low
      GL diet may be a particularly effective dietary regimen for overweight Latino children at
      risk for T2DM, who have a high consumption of processed and refined carbohydrate foods. The
      overall aim of this project is to determine the hormonal, metabolic, and body composition
      changes that occur during a two-year period of consumption of low-GL meals compared to low
      fat meals among Latino children at risk for T2DM. Our specific aims are:

      - Specific Aim 1: To study the short- and long-term effects of a low-GL diet on insulin
      sensitivity in overweight Latino children at risk for T2DM.

      Hypothesis 1: Insulin sensitivity will increase to a greater extent in children randomized to
      a low-GL diet than in children randomized to a reduced-fat meal prescription after 3, 12, and
      24 months. The increase in insulin sensitivity found with a low-GL diet will not be fully
      explained by changes in BMI alone.

      - Specific Aim 2: To determine the short- and long-term effects of a low-GL diet on BMI
      z-score and body fat changes in overweight Latino children at risk for T2DM.

      Hypothesis 2: BMI z-score and body fat proportion will decrease to a greater extent in
      children randomized to a low-GL diet than in children randomized to a reduced-fat meal
      prescription after 3, 12, and 24 months observation periods.

      - Specific Aim 3: To examine the effects of low-GL diet on markers of metabolic risk in
      overweight Latino children at risk for T2DM.

      Hypothesis 3: Both traditional risk factors (e.g. systolic blood pressure, LDL-cholesterol,
      and triglycerides) and non-traditional risk factors (e.g. inflammatory [C-reactive protein,
      fibrinogen, and Plasminogen activating inhibitor -1], and adipocyte-derived factors
      [adiponectin, resistin, and free fatty acids]), related to insulin sensitivity will be lower
      in the low-GL meal group compared to the reduced-fat meal group at 3, 12, and 24 months.

      - Specific Aim 4: To examine the subjective, hormonal, and metabolic responses of obese
      Hispanic youth to consumption of low-glycemic load and high glycemic load meals under
      controlled, standardized conditions.

      Hypothesis 4: compared to the group fed high glycemic load meals, the low glycemic load group
      will have lower glucose and lower insulin responses, the low glycemic load group will report
      less hunger before their meals and greater satiety after their meals, and the low glycemic
      load group will consume less energy from a post-meal ad libitum snack platter.

      Latino children ages 7-14y with BMI≥95th percentile and at-risk for T2DM will be randomly
      assigned either to a low-GL or a low-fat dietary plan for 2 years. Subjects will also
      participate in a culturally competent, family-based intervention program which includes
      behavior modification and enhanced physical activity. The frequence of intervention will
      consist of weekly visits for 12 weeks (Phase 1), monthly visits for 9 months (Phase 2), and
      3-monthly visits for 12 months (Phase 3).

      After completion of Phase 1, subjects will be admitted to the GCRC over a 24-hour period to
      participate in a meal study. Subjects will be provided with standardized meals consisting of
      either low-glycemic load (to the low-GL group) or high-glycemic load (to the high-GI group),
      and their subjective, hormonal, and metabolic responses will be assessed.
    

Intervention name(s): Low Glycemic Load Diet versus Low Fat Diet
Intervention type(s): Behavioral
Intervention description(s): We propose a randomized controlled clinical trial to evaluate the effectiveness of a low-glycemic load diet versus low-fat diet on insulin sensitivity, body composition, and other hormonal and biochemical measures. The culturally competent and family-based Intervention program has a dietary experimental component (low-glycemic load versus low-fat diet), as well as elements of physical activity, reduction in sedentary behavior and behavior modification. The nutrition training sessions are divided into 12 modules taught over a 12-week course. Care has been taken to make the content and intensity of the low-fat and low-glycemic load programs comparable. Both treatments include 12 weekly sessions, followed by nine monthly, and four 3-monthly sessions.
Participants are obese (BMI ≥95th percentile for age and sex) Hispanic American children ages 7-14 years.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Low Glycemic Load diet; Low Glycemic Index diet; Low Fat diet; Obese Hispanic American children and adolescents; At risk for type 2 diabetes mellitus