Marlene Busko

September 20, 2017

LISBON, PORTUGAL — Patients with type 2 diabetes were less likely to develop a "potentially catastrophic" aortic aneurysm, and they had better short-term survival after an aortic aneurysm rupture compared with individuals without diabetes, in a large cohort study.

Researchers matched more than 400,000 patients with type 2 diabetes in a Swedish diabetes registry with individuals of the same sex, age range, and county of residence who were free of diabetes.

The patients with type 2 diabetes had a 28% lower risk of developing an aortic aneurysm during a 7-year follow-up.  

These intriguing findings support observations in smaller studies, Tarik Avdic, MD, from the University of Gothenburg, Sweden, told Medscape Medical News at a press briefing prior to an oral presentation at the European Association for the Study of Diabetes (EASD) 2017 Annual Meeting.

This research did not look at potential mechanisms, but it supports previous smaller studies that suggest that "diabetes makes the aortic wall stronger and reduces the inflammatory response," he said.

However, patients with type 2 diabetes patients still have a higher rate of cardiovascular disease overall, including coronary artery disease and acute myocardial infarction (MI), he cautioned.

Thus, "You cannot say to your patient, 'It's good you have diabetes,' " senior author Björn Eliasson, MD, also from the University of Gothenburg, added to Medscape Medical News.

Aortic Aneurysm Finding Must Be Kept in Perspective

A ruptured aortic wall is a "catastrophic," potentially fatal event, session cochair and study coauthor Soffia Gudbjörnsdottir, University of Gothenburg, noted.

"You don't want to have it, so everything that can help us understand the mechanism is good," she said.

Patients with type 2 diabetes might have better screening for aortic aneurysm or better lipid-lowering or antihypertensive therapy, or they may have more regular visits to a clinician, cochair Naveed A Sattar, University of Glasgow, Scotland, who was not involved with the study, suggested to Medscape Medical News.

"Having said that, overall cardiovascular risk in terms of heart failure and a whole host of cardiovascular disease is substantially higher in people with diabetes," which helps put "this small finding of lower aortic aneurysms" into perspective.

"While it's good that people with diabetes may get less fatal disease from that particular complication, it will not change overall clinical practice of treating cardiovascular risk factors — such as blood pressure, lipids, cholesterol, smoking, etc — aggressively to prevent overall risk."

Diabetes and Aneurysm Risk in a Large Cohort

Previous small studies reported lower abdominal aortic aneurysm risk with type 2 diabetes, so the researchers aimed to investigate this in a larger population.

They identified 448,319 patients with type 2 diabetes who were part of the Swedish National Diabetes Register from 1998 to 2015, and they matched. each patient with five controls from five other Swedish databases (for a total of 2,251,015 controls).

About half of the individuals in both groups were women (46%), and they had a mean age of 65.

Compared with the controls, patients with diabetes were slightly less likely to be married (53% vs 56%) or have a college education (16% vs 24%).

However, patients with diabetes were more likely to have coronary artery disease (17% vs 8%), stroke (6% vs 4%), cardiovascular disease (14% vs 8%), atrial fibrillation (7% vs 4%), or acute MI (9% vs 4%).

During a mean follow-up of 7 years, 2878 patients with diabetes (0.0064%) vs 16,740 control individuals (0.0074%) had an aortic aneurysm.

Patients with type 2 diabetes had a 28% lower risk of aortic aneurysm (hazard ratio [HR], 0.72; 95% CI 0.68–0.77; < .001) and a 47% lower risk of a tear in the aortic wall, or aortic dissection (HR, 0.53; 95% CI 0.42–0.66).

On the other hand, male sex tripled the risk of an aortic aneurysm (HR, 3.36) and hypertension or being on lipid lowering medications also upped the risk (HR, 1.59 and 1.37, respectively).

Patients with type 2 diabetes also had lower risks for thoracic, abdominal, or unspecified aortic aneurysm subtypes.

Among the patients who were hospitalized for an aortic aneurysm, patients with type 2 diabetes had a 12% lower adjusted risk of death within 2 years (HR, 0.88, P < .001).

However, there was no significant between-group difference for 2-year survival after aortic dissection.

"Glycated cross-links in aortic tissue may play a protective role in progression of aortic diseases in diabetic patients," Dr Avdik and colleagues speculate.  

More research is needed to unravel this mechanism and to see whether greater efforts to lower blood pressure or stop smoking might have an even bigger impact on reducing the risk of aortic aneurysm, they note.

The authors disclose that they have no relevant financial relationships.  

European Association for the Study of Diabetes 2017 Annual Meeting. September 11, 2017; Lisbon, Portugal. Abstract 84

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