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Long-term effectiveness of lifestyle and behavioral weight loss interventions in adults with type 2 diabetes: A meta-analysis

https://doi.org/10.1016/j.amjmed.2004.05.024Get rights and content

Abstract

Background

Most persons with type 2 diabetes are overweight, and obesity worsens the metabolic and physiologic abnormalities associated with diabetes. Our objective was to assess the effectiveness of lifestyle and behavioral weight loss and weight control interventions in adults with type 2 diabetes.

Methods

Studies were obtained from searches of multiple electronic bibliographic databases, supplemented with hand searches of selected journals and consultation with experts in obesity research. Studies were included if they were published or unpublished randomized controlled trials in any language that examined weight loss or weight control strategies using one or more dietary, physical activity, or behavioral interventions, with a follow-up interval of at least 12 months. Effects were combined using a random-effects model.

Results

The 22 studies of weight loss interventions identified yielded a total of 4659 participants with a follow-up of 1 to 5 years. The pooled weight loss for any intervention in comparison with usual care among 585 subjects was 1.7 kg (95% confidence interval [CI]: 0.3 to 3.2 kg), or 3.1% of baseline body weight among 511 subjects. Among 126 persons who underwent a physical activity and behavioral intervention, those who also received a very low-calorie diet lost 3.0 kg (95% CI: −0.5 to 6.4 kg), or 1.6% of baseline body weight, more than persons who received a low-calorie diet. Among 53 persons who received identical dietary and behavioral interventions, those who received a more intense physical activity intervention lost 3.9 kg (95% CI: −1.9 to 9.7 kg), or 3.6% of baseline body weight, more than those who received a less intense or no physical activity intervention. Comparison groups often achieved substantial weight loss (up to 10.0 kg), minimizing between-group differences. Changes in glycated hemoglobin level generally corresponded to changes in weight and were not substantial when between-group differences were examined.

Conclusion

Weight loss strategies involving dietary, physical activity, or behavioral interventions were associated with small between-group improvements in weight. These results were minimized by weight loss in the comparison group, however, and examination of individual study arms revealed that multicomponent interventions, including very low-calorie diets or low-calorie diets, may hold promise for achieving weight loss in adults with type 2 diabetes.

Section snippets

Data sources

We developed a systematic review protocol using the Cochrane Collaboration's method (20). Using Medical Subject Headings and text words, we searched the following databases between the date indicated and August 2003: MEDLINE (1966), EMBASE (1980), Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1982), Educational Resources Information Center (ERIC) (1966), PsychInfo (1967), Web of Science (1981), Biosis (1969), Nutrition Abstracts and Review (1979), Cochrane Library (2002,

Results

No unpublished studies were identified (Figure 1). Two studies were excluded from our meta-analysis: one (27) fulfilled the inclusion criteria but did not provide any measure of dispersion for outcomes, and another (28) combined intervention and control groups.

The meta-analysis comprised 22 eligible studies (in 21 publications) (Table 1, Table 2); two studies were reported in one publication (43). Table 2 includes the 22 eligible studies, in addition to 15 other publications derived from the

Discussion

We found that randomized controlled trials of weight loss interventions involving diet (with or without physical activity or behavioral interventions) reported only small additional declines in weight and HbA1C level as compared with those achieved by comparison groups. A partial explanation for these small changes is that the comparison group often had moderate weight loss (up to 10.0 kg), minimizing between-group differences. Cointerventions and contamination of the comparison group, as well

Acknowledgment

The authors thank Nathalie Bousader, MD, Florence J. Dallo, MPH, and Rolanda Watkins, MPH, for assistance with abstracting data from studies. Jan Stansell, MSc, and Karla Bergerhoff, MD, were invaluable in their assistance in devising and running search strategies.

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    This study was supported by the Centers for Disease Control and Prevention, Atlanta, Georgia. With regard to the contributions of Dr. Avenell, the Health Services Research Unit is core funded by the Chief Scientist Office of the Scottish Executive Health Department; however, the views expressed here are those of the authors.

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