- Clare L Gillies, medical statistician1,
- Keith R Abrams, professor of medical statistics1,
- Paul C Lambert, senior lecturer in medical statistics1,
- Nicola J Cooper, MRC senior training fellow in health services research1,
- Alex J Sutton, reader in medical statistics1,
- Ron T Hsu, clinical senior teaching fellow in epidemiology and public health1,
- Kamlesh Khunti, clinical senior lecturer2
- 1Centre for Biostatistics and Genetic Epidemiology, Department of Health Sciences, University of Leicester, Leicester LE1 7RH
- 2Clinical Division of General Practice and Primary Health Care, Department of Health Sciences, University of Leicester
- Correspondence to: C L Gillies
- Accepted 28 November 2006
Objective To quantify the effectiveness of pharmacological and lifestyle interventions to prevent or delay type 2 diabetes in people with impaired glucose tolerance.
Data sources Medline, Embase, and the Cochrane library searched up to July 2006. Expert opinions sought and reference lists of identified studies and any relevant published reviews checked.
Study selection Randomised controlled trials that evaluated interventions to delay or prevent type 2 diabetes in individuals with impaired glucose tolerance.
Results 21 trials met the inclusion criteria, of which 17, with 8084 participants with impaired glucose tolerance, reported results in enough detail for inclusion in the meta-analyses. From the meta-analyses the pooled hazard ratios were 0.51 (95% confidence interval 0.44 to 0.60) for lifestyle interventions v standard advice, 0.70 (0.62 to 0.79) for oral diabetes drugs v control, 0.44 (0.28 to 0.69) for orlistat v control, and 0.32 (0.03 to 3.07) for the herbal remedy jiangtang bushen recipe v standard diabetes advice. These correspond to numbers needed to treat for benefit (NNTB) and harm (NNTH) of 6.4 for lifestyle (95% credible interval, NNTB 5.0 to NNTB 8.4), 10.8 for oral diabetes drugs (NNTB 8.1 to NNTB 15.0), 5.4 for orlistat (NNTB 4.1 to NNTB 7.6), and 4.0 for jiangtang bushen (NNTH 16.9 to NNTB 24.8).
Conclusions Lifestyle and pharmacological interventions reduce the rate of progression to type 2 diabetes in people with impaired glucose tolerance. Lifestyle interventions seem to be at least as effective as drug treatment.
We thank Vanessa Beck, Santiago Moreno, Julia Chernova, Ki-Shing Victor Miu, and Noriaka Sawa, who helped with translations.
Contributors: CLG is guarantor of the paper. She performed the literature search, extracted and analysed the data, and wrote the first draft of the article. All other authors contributed to the writing of the paper, and gave advice and input at all stages of the study. Additionally KRA, PCL, and KK also assisted with data extraction and analysis. The initial idea for this review came from KRA and KK.
Funding: CLG is funded jointly by the UK Medical Research Council and the Economic and Social Research Council under an interdisciplinary postgraduate research studentship in the social and medical sciences. NJC is funded by a Medical Research Council training fellowship in health services research.
Competing interests: KK has received sponsorship for attending conferences and small honorariums from pharmaceutical companies that manufacture drugs for hypoglycaemia and anti-obesity drugs.
Ethical approval: Not required.
- Accepted 28 November 2006