Researchers report that news in the October edition of Diabetes Care.
Data came from more than 34,000 adults who got their health care through Kaiser Permanente Northwest. The group included 17,000 diabetes patients.
When the study started, atrial fibrillation was more common in diabetes patients than in people without diabetes, affecting 3.6% of the diabetes patients, compared to 2.5% of those without diabetes.
The researchers then tracked everyone else -- all participants who didn't already have atrial fibrillation -- for seven years.
During that time, people with diabetes were more likely than people without diabetes to develop atrial fibrillation. That risk was higher for women than for men.
Regardless of factors including age, height, weight, blood pressure, previous history of heart disease, cholesterol levels, and hemoglobin A1c (which is used to estimate blood sugar control in recent months), women with diabetes were 26% more likely than other women to develop atrial fibrillation.
But diabetes didn't stand out as an independent risk factor for atrial fibrillation in men. That is, atrial fibrillation was more common in men with diabetes than in men without diabetes, but that gap vanished when the researchers controlled for other risk factors.
The reasons for the gender gap in the results aren't clear from this study.
"Diabetes has long been recognized as a risk factor for atrial fibrillation," write the researchers, who included Gregory Nichols, PhD, of the Kaiser Permanente Center for Health Research in Portland, Ore.
Nichols and colleagues say the gender gap in their findings was unexpected and needs further study.