All‐cause and cause‐specific mortality risk and loss in life expectancy associated with incident type 2 diabetes onset age and duration

Abstract Background Evidence on type 2 diabetes onset age and duration on mortality risk has been limited by short follow‐up, inadequate control for confounding, missing repeated measurements, and inability to cover the full range of onset age, duration, and major causes of death. Moreover, scarce data dissect how type 2 diabetes onset age and duration shape life expectancy. Methods We evaluate prospectively these topics based on 270,075 eligible participants in the Nurses’ Health Studies and Health Professionals Follow‐up Study, leveraging repeated measurements throughout up to 40 years of follow‐up. Cox models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Results In fully adjusted analyses, incident early onset type 2 diabetes (diagnosed <40 years of age) was associated with significantly higher mortality from all‐causes (HR, 95% CI was 3.16, 2.64–3.79; vs. individuals without type 2 diabetes), cardiovascular disease (6.56, 4.27–10.1), respiratory disease (3.43, 1.38–8.51), neurodegenerative disease (5.13, 2.09–12.6), and kidney disease (8.55, 1.98–36.9). The relative risk elevations declined dramatically with each higher decade of age at diagnosis for deaths from most of these causes, though the absolute risk difference increased continuously. A substantially higher cumulative incidence of mortality and a greater loss in life expectancy were associated with younger age at type 2 diabetes diagnosis. Longer disease duration was associated with generally higher relative and absolute risk of mortality. Conclusion Early onset of type 2 diabetes and longer disease duration are associated with substantially increased risk of all‐cause and cause‐specific mortality and greater loss in life expectancy.