The authors note that the majority of studies (21/27) evaluated intensive trial-based interventions or intensive translations of trial interventions (e.g. the US Diabetes Prevention Program [USDPP]). However NICE advocates a more pragmatic approach to lifestyle programmes, and only three studies in this review are relevant comparators in terms of duration and intensity of lifestyle intervention, reporting a wide range of cost-effectiveness (from £3215/QALY to £76,566/QALY).
They comment on how the included studies varied widely and produced diverse results due to differences in model structure and parameter values, and to differences in health systems, types of pre-diabetes and types of lifestyle interventions included. With these caveats in mind, the main overall findings were:
· Both metformin and lifestyle interventions in people with pre-diabetes appear to be cost effective but not cost saving despite their impact on reducing diabetes incidence, with median ICERs of £8428/QALY and £7490/QALY, respectively.
· Metformin and lifestyle programmes appear equally cost effective when only the costs of the health system are taken into account, but metformin is more cost effective when costs of participants’ time (participating in and travelling to programme activities) are taken into account.
· There is insufficient evidence to deduce what intensity, duration or format or lifestyle programmes are more cost effective than others.
· Programmes that evaluated costs and benefits over ≥25 years were more cost effective than those that looked at ≤10 years.
The conclude that although there is some evidence that diabetes prevention programmes are cost effective, the evidence base to date provides few clear answers regarding design of prevention programmes.
The NICE public health guideline on prevention of type 2 diabetes in people at high risk (PH38) was originally published in July 2012 and updated in September 2017. For the update, new recommendations were added on lifestyle-change programmes (recommendations 1.5.5 and 1.5.6) and the recommendation regarding metformin (1.19.1) was changed.
The 2012 version of the guideline recommended that intensive lifestyle-change programmes should be offered to people at high risk of type 2 diabetes. The new recommendations recognise that commissioners may need to prioritise subsets of the population for these programmes, in order to make the most of resources. Implementing these recommendations will allow the NHS Diabetes Prevention Programme to be initially targeted at groups of the population who will benefit most, in a way that is consistent across the UK.
The results of economic modelling showed that lifestyle-change programmes are more clinically and cost effective than metformin; however metformin is cost effective in the high-risk population overall, and for most subgroups, when compared to control. The updated recommendation is as follows:
1.19.1 Use clinical judgement on whether (and when) to offer metformin to support lifestyle change for people whose HbA1c or fasting plasma glucose blood test results have deteriorated if:
· this has happened despite their participation in intensive lifestyle-change programmes or
· they are unable to participate in an intensive lifestyle-change programme, particularly if they have a BMI greater than 35 [the model showed that metformin is particularly clinically and cost effective for this group]