Meta-analysisEfficacy of lifestyle interventions in reducing diabetes incidence in patients with impaired glucose tolerance: A systematic review of randomized controlled trials
Introduction
Worldwide, the incidence of type 2 diabetes mellitus is increasing. The World Health Organization has predicted a global increase in diabetes prevalence of 39% between the years 2000 and 2030. The statistic shows that the number will increase to 366 million people in the year 2030 [1].
Type 2 diabetes results from the combination of genetic predisposition, behavioral, and environmental risk factors [2]. There is strong evidence that such modifiable risk factors like bad health behaviors, nutrition, obesity, and physical inactivity are the main environmental determinants of the disease [3], [4], [5], [6], [7], [8], [9].
Impaired glucose tolerance (IGT) is an intermediate category between normal glucose tolerance and diabetes. Subjects with impaired glucose tolerance have an increased risk of developing type 2 diabetes, and therefore form an important high-risk target group for intervention aimed at preventing diabetes [3], [10], [11].
Early studies involving lifestyle intervention showed beneficial effects in diabetes high risk groups [12], [13]. However there is no level of evidence 1 study to confirm the effect of lifestyle interventions in IGT patients. The aim of this study was to assess the efficacy of lifestyle intervention to prevent the onset of type 2 diabetes in IGT patients, using systematic review.
Section snippets
Search strategy and selection criteria
We conducted a systematic review of the available literature in accordance with the QUORUM guidelines and Cochrane Handbook for Systematic Reviews of Interventions [14], [15]. PICO criteria were used to construct the clinical questions [16], [17]. Inclusion and exclusion criteria were defined. Main inclusion criteria were impaired glucose tolerance (IGT), randomized controlled trial, lifestyle intervention with control group, observation time > 6 months and outcome defined as diabetes incidence.
Result
Overall, 7 randomized controlled trials (25 publications) were identified, in which they provide the information of a total of 5663 patients. The identified trials including follow-up time, drop-out rate, and patient characteristics at randomization are shown in Table 1. The flowchart in Fig. 1 shows the identification process. Kappa Cohens for title analysis were К = 0.77, (CI = 0.71–0.83), abstract-analysis К = 0.81 (CI = 0.64–0.92) and full-text analysis К = 0.78 (CI = 0.57–0.98). According to SIGN 50
Discussion
The main finding of this study is that all included studies found a reduction in diabetes type 2 incidence by lifestyle intervention in impaired glucose tolerance patients. The overall incidence of diabetes was reduced by 4% to 21.7% in the intervention group compared with the control group depending on the study and follow-up years. A significant decrease in mortality and morbidity rates was not reported. None of the included studies performed an analysis according to QALY parameters.
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Conclusion
Consequently, this study added information on how lifestyle intervention produced significant improvement in diabetes incidence but no improvement in mortality, morbidity or other known risk factors for diabetic complications. However, according to the heterogeneity of study designs and multiple influence factors, this study can not give a definitive answer to the question of whether primary prevention of Type 2 diabetes reduces the diabetes incidence, but suggestions could be proposed. To
Author contributions
Uzung Yoon: designed and conduct of the study, data collection and analysis, data interpretation and manuscript writing.
Lai Lai Kwok: data collection and analysis, data interpretation and manuscript writing.
Athanasios Magkidis: data collection and analysis, data interpretation.
Role of the funding source
No funding
Funding
None.
Conflicts of interest
The authors declare that they have no competing interests including financially related interest.
Non-financial competing interests.
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