Aims/hypothesis: Few studies examine the association between age at diagnosis and subsequent complications from type 2 diabetes. This paper aims summarise the risk of mortality, macrovascular and microvascular complications associated with age at diagnosis of type 2 diabetes.
Methods: Data were sourced from Medline and All EBM (Evidence Based Medicine) databases from inception to July 2018. Observational studies, investigating the effect of age at diabetes diagnosis on macrovascular and microvascular diabetes complications in adults with type 2 diabetes were selected according to pre-specified criteria. Two investigators independently extracted data and evaluated all studies. If data were not reported in a comparable format, data were obtained from authors, presented as minimally adjusted odds ratios (and 95% confidence intervals) per one year increase in age at diabetes diagnosis, adjusted for current age for each outcome of interest. The study protocol was recorded with PROSPERO International prospective register of systematic reviews (CRD42016043593).
Results: Data from 26 observational studies comprising 844 081 individuals from 30 countries were included. Random effects meta-analyses with inverse variance weighting were used to obtain the pooled odds ratios. Age at diabetes diagnosis was inversely associated with risk of all-cause mortality, macrovascular and microvascular disease (all p<0.001). Each one-year increase in age at diabetes diagnosis was associated with a 4, 3 and 5% decreased risk of all-cause mortality, macrovascular disease and microvascular disease respectively, adjusted for current age. The effects were consistent for the individual components of the composite outcomes (all p<0.001).
Conclusions/interpretation: Younger rather than older, age at diabetes diagnosis was associated with higher risk of mortality and vascular disease. Early and sustained interventions to delay type 2 diabetes onset and improve glycaemia and cardiovascular risk profiles of those already diagnosed are essential to reduce morbidity and mortality.