Association between the English National Health Service Diabetes Prevention Programme and incident multiple long-term conditions

Existing evaluations of the National Health Service Diabetes Prevention Programme (NHS DPP) in England have demonstrated associated reductions in body weight, hemoglobin A1c and incident type 2 diabetes (T2D). In this study, we examined associations between completion of the NHS DPP and incidence of T2D and 30 other long-term conditions (LTCs), including LTCs considered linked to the program's interventional goals of body weight reduction, increased physical activity and improved diet quality (LTC-L) and LTCs considered to be possibly linked to those goals (LTC-PL). We found that completers of the NHS DPP had lower incidences of T2D, LTC-L and LTC-PL compared to non-attenders. Although these associations attenuated over time, they remained significant for all outcomes at 24 months with an odds ratio of 0.53 (95% confidence interval: 0.48-0.59) for T2D and rate ratios of 0.79 (0.74-0.84) and 0.80 (0.74-0.88) for LTC-L and LTC-PL, respectively. However, we were not able to directly conclude whether lower incidence rates were a direct result of completing the NHS DPP or due to residual bias stemming from unmeasured confounding and imprecision in the estimation of diagnosis.