Physical activity, obesity, and the incidence of type 2 diabetes in a high-risk population

This study, examining the longitudinal relation among physical activity, body mass index, and development of type 2 diabetes in a high-risk population, is unique because diabetes was determined by oral glucose tolerance testing rather than by self-report. A physical activity questionnaire assessing past year leisure and occupational activity was administered to 1,728 nondiabetic Pima individuals aged 15-59 years as part of a series of clinic examinations in the Gila River Indian Community from 1987 to 2000. During an average follow-up period of 6 years, 346 subjects developed diabetes. Using time-dependent Cox proportional hazards modeling adjusting for age, the authors found that total activity was related to diabetes incidence in women and men (p < 0.05 in women only). After additional adjustment for body mass index, the relation between activity and diabetes incidence was weakened in both men and women. When the age-adjusted diabetes incidence rates were examined by levels of activity stratified by tertile of body mass index, the diabetes incidence rate remained lower in more active than in less active men and women from all body mass index groups, with the exception of the middle body mass index tertile in men (p < 0.05 in women only). These results suggest that the adoption and maintenance of a physically active lifestyle can play a significant role in preventing type 2 diabetes.     

Genome-wide linkage analysis of serum adiponectin in the Pima Indian population

Adiponectin is a circulating protein secreted by adipocytes and is thought to have insulin-sensitizing effects. We present genetic analysis of adiponectin levels in 517 Pima Indians without diabetes (from 162 families, 750 sib-pairs). Adiponectin concentrations were heritable, with 39% of the variance of age- and sex-adjusted adiponectin potentially accounted for by additive genetic influences in this population. In genome-wide linkage analyses, suggestive linkage (logarithm of odds [LOD] = 3.0) of adiponectin adjusted for age and sex was found on chromosome 9p at 18 cM. Linkage was also present after inclusion of adiponectin concentrations of siblings with type 2 diabetes not treated pharmacologically (total siblings 582, 182 families, 860 sib-pairs: LOD = 3.5). Tentative evidence of linkage was also found on chromosomes 2 (LOD = 1.7 at 89 cM), 3 (LOD = 1.9 at 124 cM), and 10 (LOD = 1.7 at 70 cM), offering some support to findings of a previous genome-wide scan of adiponectin. Our data suggest that quantitative trait loci on chromosomes 2, 3, 9, and 10 may influence circulating adiponectin concentrations in the Pima population.     

Interventions aimed at preventing and reducing overweight/obesity among children and adolescents: a meta‐synthesis

The prevalence of child and adolescent obesity has been a major worldwide problem for decades. To stop the number of youth with overweight/obesity from increasing, numerous interventions focusing on improving children's weight status have been implemented. The growing body of research on weight‐related interventions for youth has been summarized by several meta‐analyses aiming to provide an overview of the effectiveness of interventions. Yet, the number of meta‐analyses is expanding so quickly and overall results differ, making a comprehensive synopsis of the literature difficult. To tackle this problem, a meta‐synthesis was conducted to draw informed conclusions about the state of the effectiveness of interventions targeting child and adolescent overweight. The results of the quantitative synthesis of 26 meta‐analyses resulted in a standardized mean difference (SMD) of ?0.12 (95%CI: ?0.16, ?0.08). Several moderator analyses showed that participant and intervention characteristics had little impact on the overall effect size. However, a moderator analysis distinguishing between obesity treatment and obesity prevention studies showed that obesity treatment interventions (SMD: ?0.048, 95%CI: ?0.60, ?0.36) were significantly more effective in reducing body mass index than obesity prevention interventions (SMD: ?0.08, 95%CI: ?0.11, ?0.06). Overall, the results of this meta‐synthesis suggest that interventions result in statistically significant effects albeit of relatively little clinical relevance.