Mortality risk for males and females with type 1 and type 2 diabetes in Aotearoa New Zealand: a national cohort study

Diabetes mellitus substantially contributes to early morbidity and mortality, but there is a paucity of contemporary Aotearoa New Zealand-specific research that accurately quantifies this risk. Using a comprehensive repository of linked national administrative and survey data, this study aimed to estimate the whole population excess risk in mortality associated with diabetes, stratified by diabetes type and sex, adjusted for important sociodemographic and social determinants of health variables. Overall, 4,437,453 people alive on 31 December 2014 were followed until 31 December 2019. Of these, 259,548 (5.8%) had diabetes (15,729 with type 1 diabetes [T1D] and 243,819 with type 2 diabetes [T2D]) and 149,856 (3.4%) died over the study period. Adjusted Cox’s proportional hazards models revealed significant mortality risk associated with both T1D and T2D, which was modified by increasing age and area-based deprivation level. The mortality hazard associated with diabetes was greatest amongst those aged 0–19 years. While the overall mortality risk increased with increasing deprivation level, this risk appeared to be amplified for those with T1D yet attenuated for people with T2D. Patterns were similar between males and females. These findings highlight the need for interventions that prioritize younger and socioeconomically disadvantaged populations with diabetes.