Justin B. Echouffo‐Tcheugui

Background The relation between age at diagnosis of type 2 diabetes (T2D) and hospitalization for heart failure (HHF) is unclear. We assessed the association between age at diagnosis of T2D and HHF. Methods and Results We conducted a population‐based cohort study using administrative health databases from the Canadian province of Ontario, including participants without prior heart failure. We identified people with new‐onset T2D between April 1, 2005 and March 31, 2015, and matched each person with 3 diabetes‐free adults, according to birth year and sex. We estimated adjusted hazard ratios (HRs) and rate ratios (RRs) for the association between age at T2D diagnosis and incident HHF, which was assessed until March 31, 2020. Among 743 053 individuals with T2D and 2 199 539 matched individuals without T2D, 126 241 incident HHF events occurred over 8.9 years. T2D was associated with a greater adjusted hazard of HHF at younger ages (eg, HR at age 30 years: 6.94 [95% CI, 6.54–7.36]) than at older ages (eg, HR at age 60 years: 2.50 [95% CI, 2.45–2.56]) relative to matched individuals. Additional adjustment for mediators (hypertension, coronary artery disease, and chronic kidney disease) marginally attenuated this relationship. Age at T2D diagnosis was associated with a greater number of HHF events relative to matched individuals at younger ages (eg, RR at age 30 years: 6.39 [95% CI, 5.76–7.08]) than at older ages (eg, RR at age 60 years: 2.65 [95% CI, 2.54–2.76]). Conclusions Younger age at T2D diagnosis is associated with a disproportionately elevated HHF risk relative to age‐matched individuals without T2D.