Dose-Dependent Associations of Dietary Glycemic Index, Glycemic Load, and Fiber With 3-Year Weight Loss Maintenance and Glycemic Status in a High-Risk Population: A Secondary Analysis of the Diabetes Prevention Study PREVIEW

Abstract

Objective: To examine longitudinal and dose-dependent associations of dietary glycemic index (GI), glycemic load (GL), and fiber with body weight and glycemic status during 3-year weight loss maintenance (WLM) in adults at high risk of type 2 diabetes.

Research design and methods: In this secondary analysis we used pooled data from the PREVention of diabetes through lifestyle Intervention and population studies in Europe and around the World (PREVIEW) randomized controlled trial, which was designed to test the effects of four diet and physical activity interventions. A total of 1,279 participants with overweight or obesity (age 25-70 years and BMI ≥25 kg ⋅ m-2) and prediabetes at baseline were included. We used multiadjusted linear mixed models with repeated measurements to assess longitudinal and dose-dependent associations by merging the participants into one group and dividing them into GI, GL, and fiber tertiles, respectively.

Results: In the available-case analysis, each 10-unit increment in GI was associated with a greater regain of weight (0.46 kg ⋅ year-1; 95% CI 0.23, 0.68; P < 0.001) and increase in HbA1c. Each 20-unit increment in GL was associated with a greater regain of weight (0.49 kg ⋅ year-1; 0.24, 0.75; P < 0.001) and increase in HbA1c. The associations of GI and GL with HbA1c were independent of weight change. Compared with those in the lowest tertiles, participants in the highest GI and GL tertiles had significantly greater weight regain and increases in HbA1c. Fiber was inversely associated with increases in waist circumference, but the associations with weight regain and glycemic status did not remain robust in different analyses.

Conclusions: Dietary GI and GL were positively associated with weight regain and deteriorating glycemic status. Stronger evidence on the role of fiber is needed.

Trial registration: ClinicalTrials.gov NCT01777893.

© 2021 by the American Diabetes Association.

Figures

Figure 1

Longitudinal associations of cumulative average GI (each 10 unit) with yearly weight regain and changes in markers of glycemic status during WLM. Model 1 was adjusted for age, sex, ethnicity, anthropometric outcomes or body composition, and markers of glycemic status at 8 weeks, BMI at the start of WLM (8 weeks), and time as fixed effects and intervention center and participant identifier as random effects. Model 2 was additionally adjusted for time-varying accelerometry-measured PA and time-varying self-reported energy intake (kcal ⋅ day−1) and dietary components including percentage of energy from fat, protein, fiber, and alcohol (all in E%). Model 3 was additionally adjusted for time-varying yearly changes in BW. *Yearly mean change and 95% CI of main effects indicating the increase in anthropometric outcomes or body composition or markers of glycemic status increased per year by 10-unit increment in GI. †P values for main effects.

Figure 2

Changes in BW and markers of glycemic status over time during WLM by tertiles of cumulative average GI, GL, and fiber. Values are estimated marginal mean and 95% CI in changes in BW (kg) (A) and HbA1c (%) (B) by GI tertiles, changes in BW (kg) (C) and HbA1c (%) (D) by GL tertiles, and changes in BW (kg) (E) and HbA1c (%) (F) by fiber tertiles. We performed analyses using a linear mixed model with repeated measurements with adjustment for age, sex, ethnicity, anthropometric outcomes or body composition, and markers of glycemic status at the start of WLM (8 weeks); BMI at 8 weeks; and time, time-varying accelerometry-measured PA, and self-reported energy intake (kcal ⋅ day−1) and dietary components including percentage of energy from fat, protein, fiber, or carbohydrate, and alcohol (all in E%) as fixed effects and with participant identifier and intervention center as random effects. For markers of glycemic status, the models were additionally adjusted for time-varying weight change. Time-by-tertile group interaction terms were added. Main effects, time effects, and time-by-tertile group interaction were reported. Post hoc analyses with multiple comparisons with Bonferroni adjustment were performed to compare the tertiles at each time point where appropriate. Values with different lowercase letters (a, b, and c) are significantly different (P < 0.05).

Figure 3

Longitudinal associations of cumulative average GL (each 20 unit) with yearly weight regain and changes in markers of glycemic status during WLM. Analyses were performed with use of a linear mixed model with repeated measurements. Model 1 was adjusted for age, sex, ethnicity, weight- or glycemic status–related outcomes at the start of WLM (8 weeks), BMI at 8 weeks, and time as fixed effects and intervention center and participant identifier as random effects. Model 2 was additionally adjusted for time-varying accelerometry-measured PA and time-varying self-reported energy intake (kcal ⋅ day−1) and dietary components including intake of fat, protein, fiber, and alcohol (all in E%). Model 3 was additionally adjusted for time-varying yearly changes in BW. *Yearly mean change and 95% CI of main effects indicating the amount of increase in anthropometric outcomes or body composition or markers of glycemic status increased per year by 20-unit increment in GL. †P values for main effects.