TOPLINE:

In a cohort of 404,026 adults with diabetes in Sweden, type 1 diabetes (T1D) was associated with a higher risk for cardiovascular disease than type 2 diabetes (T2D) among adults older than 60 years, whereas the opposite phenomenon was observed among those younger than 50 years. Longer diabetes duration in those with T1D appeared as a key determinant of the higher risk for cardiovascular disease in this population.

METHODOLOGY:

• Researchers in Sweden conducted a nationwide, longitudinal cohort study to compare the risk for cardiovascular disease and mortality between 38,351 patients with T1D (median age, 43 years; 56.1% men; median T1D duration, 22 years) and 365,675 patients with T2D (median age, 68 years; 58.1% men; median T2D duration, 8 years).
• Patients in both diabetes cohorts were also matched to control individuals without diabetes from the general population.
• All inpatient and outpatient hospital visits were tracked for a period of 5 years to capture incidences of major cardiovascular disease events and deaths in patients with diabetes.
• The primary outcome was a composite of fatal or non-fatal cardiovascular events, such as myocardial infarction, heart failure, stroke, and cardiovascular death; secondary outcomes examined these events separately.

TAKEAWAY:

• Overall, patients with T1D had a higher overall risk for the primary composite outcome than those with T2D; when compared with matched control individuals, the risk for all cardiovascular diseases was the highest in patients with T1D, followed by those with T2D.
• Compared with T1D, T2D was linked to a higher risk for overall cardiovascular disease, myocardial infarction, and heart failure among patients younger than 50 years (hazard ratio, 1.23, 1.54, and 1.60, respectively; P < .05 for all) but linked to a lower risk for overall cardiovascular disease, myocardial infarction, cardiovascular mortality, and all-cause mortality among those older than 60 years.
• After adjusting for multiple cardiovascular risk factors, T2D was associated with a higher risk for all cardiovascular diseases and all-cause mortality than T1D; however, when the diabetes duration was removed from the model, T1D carried a higher risk for all cardiovascular diseases, underscoring the duration as a key contributor.
• Female sex, higher levels of physical activity, higher income, and ongoing lipid-lowering medication use were linked to a reduced risk for most outcomes.

IN PRACTICE:

"In addition to optimising glycaemic control to reduce cumulative exposure to hyperglycaemia, the present results underscore the importance of timely management of any known cardiovascular risk (eg, overweight, smoking, hypertension, and dyslipidaemia), for both types of diabetes," an expert wrote in an accompanying commentary.

"A better understanding of the clinical course of type 1 diabetes and its complications could help inform public policy, and guidelines to support consistent care across different countries and health-care systems," they added.

SOURCE:

This study was led by Vagia Patsoukaki, MD, Clinical Diabetology and Metabolism, Uppsala University, Uppsala, Sweden. It was published online on August 25, 2025, in The Lancet Diabetes & Endocrinology.

LIMITATIONS:

The criteria used to identify individuals with diabetes cannot entirely preclude misclassification. An imbalance in age distribution existed, with the T2D population being older than the T1D population. The cohort primarily consisted of Swedish-born individuals, limiting the generalisability to populations with different ethnicities and demographics.

DISCLOSURES:

This study was supported by the Swedish Heart and Lung Foundation, the Swedish Research Council, and ALF grants at the Uppsala University Hospital. Some authors reported receiving personal fees, honoraria, research support, consulting fees, and lecture honoraria and having other ties with various pharmaceutical and healthcare companies. One author reported serving as the director of the Swedish National Diabetes Register.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.