Twenty-Year Temporal Trends in Risk of Ischemic Stroke in Incident Type 2 Diabetes: A Danish Population-Based Cohort Study

Objective
We examined temporal trends in risk of first-time ischemic stroke in patients with incident type 2 diabetes (T2DM) and no prior atherosclerotic cardiovascular disease (ASCVD). 

Research Design and Methods
Using nationwide health registries, we identified all patients with incident T2DM without a prior hospital diagnosis of ASCVD from 1996-2015 in Denmark. Patients were assigned to 5-year periods based on the date of T2DM diagnosis and were followed for 5 years. Each patient was matched by sex and age with up to 3 individuals from the general population. Temporal trends in ischemic stroke were examined using Cox regression to compute hazard ratios (HRs). Temporal use of prophylactic cardiovascular medications was also assessed. 

Results
The study comprised 288,825 patients with incident T2DM and 782,232 general population individuals. From 1996-2000 to 2011-2015, the 5-year risk of first-time ischemic stroke was approximately halved in the T2DM cohort (5.2% vs. 2.7%, sex- and age-adjusted HR 0.52 [95% CI 0.49-0.55]). Patients diagnosed in 2011-2015 had increased risk of ischemic stroke compared to general population individuals, however, the risk difference narrowed over time (5.2% vs. 2.9% in 1996-1999 [difference 2.3%]; 2.7% vs. 2.0% in 2011-2015 [difference 0.7%]). Use of prophylactic cardiovascular medications increased markedly during the overall study period, especially use of statins (5% to 50%) and multiple antihypertensive drugs (18% to 33%).

Conclusions
From 1996 to 2015, the 5-year risk of first-time ischemic stroke was approximately halved in patients with incident T2DM and no prior ASCVD, coinciding with markedly increased use of prophylactic cardiovascular medications.