School of Health and Related Research (ScHARR), University of Sheffield, Sheffield, UK.
Health Technol Assess. 2012 Aug;16(33):1-236, iii-iv. doi: 10.3310/hta16330.
The prevalence of type 2 diabetes mellitus (T2DM) is increasing in the UK and worldwide. Before the onset of T2DM, there are two conditions characterised by blood glucose levels that are above normal but below the threshold for diabetes. If screening for T2DM in introduced, many people with impaired glucose tolerance (IGT) will be found and it is necessary to consider how they should be treated. The number would depend on what screening test was used and what cut-offs were chosen.
To review the clinical effectiveness and cost-effectiveness of non-pharmacological interventions, including diet and physical activity, for the prevention of T2DM in people with intermediate hyperglycaemia.
Electronic databases, MEDLINE (1996-2011), EMBASE (1980-2011) and all sections of The Cochrane Library, were searched for systematic reviews, randomised controlled trials (RCTs) and other relevant literature on the effectiveness of diet and/or physical activity in preventing, or delaying, progression to T2DM.The databases were also searched for studies on the cost-effectiveness of interventions.
The review of clinical effectiveness was based mainly on RCTs, which were critically appraised. Subjects were people with intermediate hyperglycaemia, mainly with IGT. Interventions could be diet alone, physical activity alone, or the combination. For cost-effectiveness analysis, we updated the Sheffield economic model of T2DM. Modelling based on RCTs may not reflect what happens in routine care so we created a 'real-life' modelling scenario wherein people would try lifestyle change but switch to metformin after 1 year if they failed.
Nine RCTs compared lifestyle interventions (predominantly dietary and physical activity advice, with regular reinforcement and frequent follow-up) with standard care. The primary outcome was progression to diabetes. In most trials, progression was reduced, by over half in some trials. The best effects were seen in participants who adhered best to the lifestyle changes; a scenario of a trial of lifestyle change but a switch to metformin after 1 year in those who did not adhere sufficiently appeared to be the most cost-effective option.
Participants in the RCTs were volunteers and their results may have been better than in general populations. Even among the volunteers, many did not adhere. Some studies were not long enough to show whether the interventions reduced cardiovascular mortality as well as diabetes. The main problem is that we know what people should do to reduce progression, but not how to persuade most to do it.
In people with IGT, dietary change to ensure weight loss, coupled with physical activity, is clinically effective and cost-effective in reducing progression to diabetes.
The National Institute for Health Research Health Technology Assessment programme.
2 型糖尿病（T2DM）在英国和全球的患病率正在上升。在 T2DM 发病之前，有两种情况的血糖水平高于正常值，但低于糖尿病的阈值。如果引入 T2DM 的筛查，将会发现许多糖耐量受损（IGT）的人，因此有必要考虑如何对他们进行治疗。人数将取决于使用何种筛查测试以及选择何种截止值。
综述非药物干预（包括饮食和体力活动）在预防中间高血糖人群发生 T2DM 方面的临床有效性和成本效益。
电子数据库，包括 MEDLINE（1996-2011 年）、EMBASE（1980-2011 年）和 Cochrane 图书馆的所有部分，均检索了关于饮食和/或体力活动在预防或延缓进展为 T2DM 方面有效性的系统评价、随机对照试验（RCT）和其他相关文献。还对干预措施的成本效益进行了研究。
临床效果的综述主要基于 RCT，对其进行了严格评价。研究对象为中间高血糖人群，主要为 IGT 人群。干预措施可以是单独的饮食、单独的体力活动或两者的结合。对于成本效益分析，我们更新了 T2DM 的谢菲尔德经济模型。基于 RCT 的建模可能无法反映常规护理中的情况，因此我们创建了一个“现实生活”建模场景，其中人们会尝试生活方式改变，但如果 1 年后失败，他们会转而服用二甲双胍。
9 项 RCT 比较了生活方式干预（主要是饮食和体力活动建议，定期加强和频繁随访）与标准护理。主要结局是进展为糖尿病。在大多数试验中，进展都有所减少，有些试验中减少了一半以上。在最遵守生活方式改变的参与者中效果最好；如果没有充分遵守，则在 1 年后转而服用二甲双胍的试验方案似乎是最具成本效益的选择。
RCT 中的参与者是志愿者，他们的结果可能优于一般人群。即使在志愿者中，许多人也没有遵守。一些研究的时间不够长，无法确定干预措施是否能降低心血管死亡率和糖尿病发病率。主要问题是我们知道人们应该做些什么来减少进展，但不知道如何说服大多数人去做。
在 IGT 人群中，通过饮食改变以确保减肥，加上体力活动，在减少向糖尿病的进展方面具有临床有效性和成本效益。
英国国家卫生研究院健康技术评估计划。
