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Using Insulin Increases Stroke Risk in A-Fib

Investigation supports that early diabetes has lower thromboembolic risk than later.

Diabetes is a known risk predictor for thromboembolic events in patients with atrial fibrillation (AF), but no study has explored the prognostic weight of insulin in this setting.

This study evaluated the differential role of insulin versus no insulin therapy on thromboembolic risk in patients with diabetes and AF.

They accessed individual patient data from the prospective, real-world, multicenter PREFER in AF (European Prevention of thromboembolic events-European Registry in Atrial Fibrillation). They compared the rates of stroke/systemic embolism at one year according to diabetes status (no diabetes, diabetes without insulin therapy, diabetes on insulin therapy).

For patients with atrial fibrillation (AF), diabetes requiring insulin is associated with an increased risk of stroke/systemic embolism. This was not the case for diabetes patients who do not require insulin treatment. Giuseppe Patti, M.D., from the Campus Bio-Medico University of Rome, and colleagues examined the differential role of insulin versus no insulin therapy on thromboembolic risk in a cohort of patients with AF. The authors compared the rates of stroke/systemic embolism at one year according to diabetes status. Data were included for 5,717 patients; 1,288 of these had diabetes, of whom 22.4 percent were on insulin.

For patients with diabetes who were on insulin, there was a significantly increased risk of stroke/systemic embolism at 1 year versus either no diabetes (5.2% vs. 1.9%; hazard ratio: 2.89; 95% confidence interval: 1.67 to 5.02; p = 0.0002) or diabetes without insulin treatment (5.2% vs. 1.8%; hazard ratio: 2.96; 95% confidence interval: 1.49 to 5.87; p = 0.0019). Notably, rates of stroke/embolism were similar in patients with diabetes not receiving insulin versus patients without diabetes (hazard ratio: 0.97; 95% confidence interval: 0.58 to 1.61; p = 0.90). The selective predictive role of insulin-requiring diabetes was independent of potential confounders, including diabetes duration, and was maintained in various subpopulations, including the subgroup receiving anticoagulant therapy.

“In this cohort of anticoagulated patients with AF, the sole presence of diabetes not requiring insulin did not imply an increased thromboembolic risk,” the authors wrote. “Conversely, insulin-requiring diabetes contributed most, if not exclusively, to the overall increase of thromboembolic risk in AF.”

The findings robustly indicated that insulin-requiring diabetes, essentially type 2 diabetes, largely contributed to the overall increase of thromboembolic risk in AF, but the mere presence of diabetes without insulin treatment did not apparently convey a negative prognostic value. The investigation still supported that early diabetes has lower thromboembolic risk than later diabetes and, in our population, the reduced thromboembolic risk in patients without insulin treatment may be caused by the shorter duration of the disease.

The results may have implications in the assessment of thromboembolic risk in the AF population with diabetes and might have therapeutic implications that need to be explored in further dedicated intervention studies.

In this cohort of anticoagulated patients with AF, the sole presence of diabetes not requiring insulin did not imply an increased thromboembolic risk. Conversely, insulin-requiring diabetes contributed most, if not exclusively, to the overall increase of thromboembolic risk in AF.

Practice Pearls:

  • Diabetes is a known risk predictor for thromboembolic events in patients with atrial fibrillation.
  • For patients with diabetes who were on insulin, there was a significantly increased risk of stroke/systemic embolism at 1 year.
  • This is the first study to show that diabetes patients on insulin have an increased risk of stroke if A-Fib is present.

Journal of the American College of Cardiology. Jan. 31 2017