OBJECTIVE Dietary behavior is closely connected to type 2 diabetes. The purpose of this meta-analysis was to identify behavior change techniques (BCTs) and specific components of dietary interventions for patients with type 2 diabetes associated with changes in HbA1c and body weight.
RESEARCH DESIGN AND METHODS The Cochrane Library, CINAHL, Embase, PubMed, PsycINFO, and Scopus databases were searched. Reports of randomized controlled trials published during 1975–2017 that focused on changing dietary behavior were selected, and methodological rigor, use of BCTs, and fidelity and intervention features were evaluated.
RESULTS In total, 54 studies were included, with 42 different BCTs applied and an average of 7 BCTs used per study. Four BCTs—“problem solving,” “feedback on behavior,” “adding objects to the environment,” and “social comparison”—and the intervention feature “use of theory” were associated with >0.3% (3.3 mmol/mol) reduction in HbA1c. Meta-analysis revealed that studies that aimed to control or change the environment showed a greater reduction in HbA1c of 0.5% (5.5 mmol/mol) (95% CI −0.65, −0.34), compared with 0.32% (3.5 mmol/mol) (95% CI −0.40, −0.23) for studies that aimed to change behavior. Limitations of our study were the heterogeneity of dietary interventions and poor quality of reporting of BCTs.
CONCLUSIONS This study provides evidence that changing the dietary environment may have more of an effect on HbA1c in adults with type 2 diabetes than changing dietary behavior. Diet interventions achieved clinically significant reductions in HbA1c, although initial reductions in body weight diminished over time. If appropriate BCTs and theory are applied, dietary interventions may result in better glucose control.