Study designs of evaluations included in the review
Randomised controlled trials (RCTs) (including cluster designs) with at least 6 months' follow-up were eligible for inclusion in the review.
Specific interventions included in the review
Studies of lifestyle education programmes (combining diet and exercise, or solely dietary education) compared with a conventional programme (e.g. usual exercise with or without dietary advice) were eligible for inclusion. The majority of the included interventions combined dietary education and exercise. There were no details of exercise or dietary prescriptions.
Participants included in the review
Studies of adults who were at high risk of type 2 diabetes, defined as having impaired glucose tolerance, impaired fasting glucose, and borderline according to criteria from the Japanese Diabetes Society, were eligible for inclusion. The included studies comprised males and females aged between 39 and 58 years, with a body mass index ranging from 24 to 34. The majority of participants had impaired glucose tolerance.
Outcomes assessed in the review
Studies measuring the incidence of type 2 diabetes and/or plasma glucose levels, defined as the difference in value 2 hours after a 75-g oral glucose load (2-hour plasma glucose) at 1 year follow-up, were eligible for inclusion. Follow-up in the included studies ranged from 6 months to 6 years.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.