Life expectancy associated with different ages at diagnosis of type 2 diabetes in high-income countries : 23 million person-years of observation

Background The prevalence of type 2 diabetes is increasing rapidly, particularly among younger age groups. Estimates suggest that people with diabetes die, on average, 6 years earlier than people without diabetes. We aimed to provide reliable estimates of the associations between age at diagnosis of diabetes and all-cause mortality, cause-specific mortality, and reductions in life expectancy. Methods For this observational study, we conducted a combined analysis of individual-participant data from 19 high income countries using two large-scale data sources: the Emerging Risk Factors Collaboration (96 cohorts, median baseline years 1961-2007, median latest follow-up years 1980-2013) and the UK Biobank (median baseline year 2006, median latest follow-up year 2020). We calculated age-adjusted and sex-adjusted hazard ratios (HRs) for all-cause mortality according to age at diagnosis of diabetes using data from 1 515 718 participants, in whom deaths were recorded during 23 center dot 1 million person-years of follow-up. We estimated cumulative survival by applying age-specific HRs to age-specific death rates from 2015 for the USA and the EU. Findings For participants with diabetes, we observed a linear dose-response association between earlier age at diagnosis and higher risk of all-cause mortality compared with participants without diabetes. HRs were 2 center dot 69 (95% CI 2 center dot 43-2 center dot 97) when diagnosed at 30-39 years, 2 center dot 26 (2 center dot 08-2 center dot 45) at 40-49 years, 1 center dot 84 (1 center dot 72-1 center dot 97) at 50-59 years, 1 center dot 57 (1 center dot 47-1 center dot 67) at 60-69 years, and 1 center dot 39 (1 center dot 29-1 center dot 51) at 70 years and older. HRs per decade of earlier diagnosis were similar for men and women. Using death rates from the USA, a 50-year-old individual with diabetes died on average 14 years earlier when diagnosed aged 30 years, 10 years earlier when diagnosed aged 40 years, or 6 years earlier