# Non-coronary arterial outcomes in people with type 1 diabetes mellitus: a Swedish retrospective cohort study

## TL;DR

This study examines how type 1 diabetes affects non-coronary arterial complications in Sweden, finding that while some risks decrease, others remain low despite risk factors.

## Contribution

The study provides new insights into the relationship between type 1 diabetes and peripheral arterial outcomes, including the protective effect against aortic aneurysms.

## Key findings

- Persons with type 1 diabetes had lower risk for aortic aneurysm despite cardiovascular risk factors.
- Diabetic foot disease risk increased significantly with more risk factors present.
- Glycemic control and traditional risk factors like HbA1c and blood pressure were key contributors to peripheral arterial outcomes.

## Abstract

Observational studies on long-term trends, risk factor association and importance are scarce for type 1 diabetes mellitus and peripheral arterial outcomes. We set out to investigate trends in non-coronary complications and their relationships with cardiovascular risk factors in persons with type 1 diabetes mellitus compared to matched controls.

34,263 persons with type 1 diabetes mellitus from the Swedish National Diabetes Register and 164,063 matched controls were included. Incidence rates of extracranial large artery disease, aortic aneurysm, aortic dissection, lower extremity artery disease, and diabetic foot syndrome were analyzed using standardized incidence rates and Cox regression.

Between 2001 and 2019, type 1 diabetes mellitus incidence rates per 100,000 person-years were as follows: extracranial large artery disease 296.5–84.3, aortic aneurysm 0–9.2, aortic dissection remained at 0, lower extremity artery disease 456.6–311.1, and diabetic foot disease 814.7–77.6. Persons with type 1 diabetes mellitus with cardiometabolic risk factors at target range did not exhibit excess risk of extracranial large artery disease [HR 0.83 (95% CI, 0.20–3.36)] or lower extremity artery disease [HR 0.94 (95% CI, 0.30–2.93)], compared to controls. Persons with type 1 diabetes with all risk factors at baseline, had substantially elevated risk for diabetic foot disease [HR 29.44 (95% CI, 3.83–226.04)], compared to persons with type 1 diabetes with no risk factors. Persons with type 1 diabetes mellitus continued to display a lower risk for aortic aneurysm, even with three cardiovascular risk factors at baseline [HR 0.31 (95% CI, 0.15–0.67)]. Relative importance analyses demonstrated that education, glycated hemoglobin (HbA1c), duration of diabetes and lipids explained 54% of extracranial large artery disease, while HbA1c, smoking and systolic blood pressure explained 50% of lower extremity artery disease and HbA1c alone contributed to 41% of diabetic foot disease. Income, duration of diabetes and body mass index explained 66% of the contribution to aortic aneurysm.

Peripheral arterial complications decreased in persons with type 1 diabetes mellitus, except for aortic aneurysm which remained low. Besides glycemic control, traditional cardiovascular risk factors were associated with incident outcomes. Risk of these outcomes increased with additional risk factors present. Persons with type 1 diabetes mellitus exhibited a lower risk of aortic aneurysm compared to controls, despite presence of cardiovascular risk factors.

Swedish Governmental and the county support of research and education of doctors, the 10.13039/501100003793Swedish Heart and Lung Foundation, Sweden and Åke-Wibergs grant.