Trends in cause-specific mortality among people with type 2 and type 1 diabetes from 2002 to 2019: a Danish population-based study

Background Despite advances in primary and secondary prevention of cardiovascular disease, excess mortality persists within the diabetes population. This study explores the components of this excess mortality and their interaction with sex. Methods Using Danish registries (2002–2019), we identified residents aged 18–99 years, their diabetes status, and recorded causes of death. Applying Lexis-based methods, we computed age-standardized mortality rates (asMRs), mortality relative risks (asMRRs), and log-linear trends for cause-specific mortality. Findings From 2002 to 2019, 958,278 individuals died in Denmark (T2D: 148,620; T1D: 7830) during 84.4 M person-years. During the study period, overall asMRs declined, driven by reducing cardiovascular mortality, notably in men with T2D. Conversely, cancer mortality remained high, making cancer the leading cause of death in individuals with T2D. Individuals with T2D faced an elevated mortality risk from nearly all cancer types, ranging from 9% to 257% compared to their non-diabetic counterparts. Notably, obesity-related cancers exhibited the highest relative risks: liver cancer (Men: asMRR 3.58 (3.28; 3.91); Women: asMRR 2.49 (2.14; 2.89)), pancreatic cancer (Men: asMRR 3.50 (3.25; 3.77); Women: asMRR 3.57 (3.31; 3.85)), and kidney cancer (Men: asMRR 2.10 (1.84; 2.40); Women: asMRR 2.31 (1.92; 2.79)). In men with type 2 diabetes, excess mortality remained stable, except for dementia. In women, diabetes-related excess mortality increased by 6–17% per decade across all causes of death, except cardiovascular disease. Interpretation In the last decade, cancer has emerged as the leading cause of death among individuals with T2D in Denmark, emphasizing the need for diabetes management strategies incorporating cancer prevention. A sex-specific approach is crucial to address persistently higher relative mortality in women with diabetes. Funding Supported by Steno Diabetes Center Aarhus, which is partially funded by an unrestricted donation from the Novo Nordisk Foundation, and by The Danish Diabetes Academy.