Psychology Faculty Work


Motivational Interviewing Improves Weight Loss in Women With Type 2 Diabetes

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Diabetes Care

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OBJECTIVE—We sought to determine whether adding motivational interviewing to a behavioral weight control program improves weight loss outcomes and glycemic control for overweight women with type 2 diabetes.

RESEARCH DESIGN AND METHODS—We conducted a randomized, controlled, clinical trial in which participants all received an 18-month, group-based behavioral obesity treatment and were randomized to individual sessions of motivational interviewing or attention control (total of five sessions) as an adjunct to the weight control program. Overweight women with type 2 diabetes treated by oral medications who could walk for exercise were eligible. Primary outcomes were weight and A1C, assessed at 0, 6, 12, and 18 months.

RESULTS—A total of 217 overweight women (38% African American) were randomized (93% retention rate). Women in motivational interviewing lost significantly more weight at 6 months (P = 0.01) and 18 months (P = 0.04). Increased weight losses with motivational interviewing were mediated by enhanced adherence to the behavioral weight control program. African-American women lost less weight than white women overall and appeared to have a diminished benefit from the addition of motivational interviewing. Significantly greater A1C reductions were observed in those undergoing motivational interviewing at 6 months (P = 0.02) but not at 18 months.

CONCLUSIONS—Motivational interviewing can be a beneficial adjunct to behavioral obesity treatment for women with type 2 diabetes, although the benefits may not be sustained among African-American women.

Individuals with type 2 diabetes frequently are overweight (1–3) and experience a range of obesity-related comorbidities (4). With every unit increase in BMI, direct medical costs associated with type 2 diabetes significantly increase (5). Weight loss has been shown to improve metabolic control and other health parameters among individuals with type 2 diabetes (6,7), with greater weight loss producing greater improvements in metabolic functioning (8). However, sustained weight loss can be challenging (9), particularly for individuals with diabetes (10). African-American women experience particular difficulties in achieving weight loss (11,12), a matter of concern given high rates of obesity (13) and diabetes (14) in this group. Therefore, improving obesity treatment outcomes for overweight individuals with comorbid diabetes has been identified as a research priority (15).

Motivational interviewing (16) is a brief intervention approach demonstrated to promote better long-term outcomes for a range of health outcomes (17,18), with preliminary support as an adjunct to behavioral obesity treatment. Motivational interviewing produced significantly better glycemic control and treatment adherence and a trend toward greater short-term weight loss in a pilot study of overweight diabetic women (19). Furthermore, motivational interviewing interventions have been shown to be effective in promoting changes in diet and physical activity (20–22). Despite this promising foundation, there have been no controlled evaluations of the long-term efficacy of motivational interviewing for obesity treatment. The purpose of the current study was to determine whether the addition of motivational interviewing to a behavioral obesity treatment program for overweight women with type 2 diabetes enhances long-term weight loss and metabolic control.



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