Effect of dose of behavioral weight loss treatment on glycemic control in adults with prediabetes

Abstract

Objective: This study examined the effects of three doses of behavioral weight loss treatment, compared with a nutrition education control group, on changes in glycemic control in individuals with obesity and prediabetes.

Research design and methods: The study included 287 adults (77% female, 81% White; mean (SD) age=54.1 (10.5) years, body mass index=36.3 (3.9) kg/m2, and hemoglobin A1c (HbA1c)=5.9 (0.2%)). Participants were randomized to one of three behavioral treatment doses (high=24 sessions, moderate=16 sessions, or low=8 sessions) or to an education group (control=8 sessions). Changes in HbA1c, fasting glucose, and body weight were assessed from baseline to 6 months.

Results: Mean (99.2% credible interval (CI)) reductions in HbA1c were 0.11% (0.07% to 0.16%), 0.08% (0.03% to 0.13%), 0.03% (-0.01% to 0.07%), and 0.02% (-0.02% to 0.07%), for the high, moderate, low, and control conditions, respectively. Mean (CI) reductions in fasting blood glucose were 0.26 mmol/L (0.14 to 0.39), 0.09 mmol/L (0 to 0.19), 0.01 mmol/L (-0.07 to 0.09), and 0.04 mmol/L (-0.03 to 0.12) for the high, moderate, low, and control conditions, respectively. The high-dose treatment produced significantly greater reductions in HbA1c and fasting blood glucose than the low-dose and control conditions (posterior probabilities (pp)<0.001); no other significant between-group differences were observed. Mean (CI) reductions in body weight were 10.91 kg (9.30 to 12.64), 10.08 kg (8.38 to 11.72), 6.35 kg (5.19 to 7.69), and 3.82 kg (3.04 to 4.54) for the high, moderate, low, and control conditions, respectively. All between-group differences in 6-month weight change were significant (pps<0.001) except for the high-dose versus moderate-dose comparison.

Conclusion: For adults with obesity and prediabetes a high dose of behavioral treatment involving 24 sessions over 6 months may be needed to optimize improvements in glycemic control.

Trial registration number: NCT00912652.

Keywords: behavioral treatment; glycemic control; obesity; weight loss.

Conflict of interest statement

Competing interests: None declared. DX participated in the study while working at the University of Texas at Austin, prior to her current affiliation with the US Food and Drug Administration (FDA). Thus, study findings and conclusions were not formally disseminated by the FDA and should not be construed to represent an agency decision or policy.

Figures

Figure 1

Participant flow through screening, randomization, and data analysis. BMI, body mass index.

Figure 2

Changes (means±posterior SDs) in HbA1c (A), fasting glucose (B), and body weight (C) by treatment condition based on missing not at random (MNAR) analyses. Means that do not share subscript letters differ significantly from each other. *NOTE: The HIGH versus MOD difference in fasting glucose was significant in the missing at random (MAR) analysis (pp=0.002).