Background
Diabetes mellitus (DM) leads to a wide range of established vascular and metabolic complications which has resulted in specific prevention programmes being implemented across high-income countries. DM has been associated with increased risk of a broader set of conditions including cancers, liver disease and common infections. We aimed to examine the trends in a broad set of cause-specific hospitalisations in individuals with DM in England from 2003-2018.
Methods
We identified 309,874 individuals with DM in the Clinical Practice Research Datalink, a well described primary care database, linked to Hospital Episode Statistics inpatient data from 2003-2018.
We generated a mixed prevalence and incident DM study population through serial cross sections and follow-up over time. We used a discretised Poisson regression model to estimate annual cause-specific hospitalisation rates in men and women with DM across 17 cause groupings. We generated a 1:1 age and sex matched non-DM population to compare findings.

Findings
Hospitalisation rates were higher for all causes in persons with DM compared to those without throughout the study period. DM itself and Ischaemic Heart Disease (IHD) were the leading causes of excess hospitalisation in 2003, but by 2018, respiratory conditions, cancers and IHD were the most common causes of excess hospitalisation across men and women. Hospitalisation rates declined in almost all traditional DM complication groupings (IHD, stroke, DM, amputations) whilst generally increasing across broader conditions (cancers, infections, respiratory conditions). These differing trends resulted in a diversification in the cause of hospitalisation, such that the traditional DM complications accounted for more than 50% of hospitalisations in 2003, but only approximately 30% in 2018. In contrast, the portion of hospitalisations that broader conditions accounted for increased including respiratory infections being attributable for 12% of hospitalisations in 2018 compared to 4% in 2003.

Interpretations
Changes in the composition of excess risk and hospitalisation burden in those with DM means that preventative and clinical measures should evolve to reflect the diverse set of causes that are driving persistent excess hospitalisation in those with DM.
Funding
Wellcome Trust. The funders had no role in the study design, analysis, interpretation of data or writing of the manuscript.