Type 2 diabetes associated with brain atrophy

The duration and severity of type 2 diabetes may be associated with brain degeneration, according to a study published online April 29 by Radiology. Contrary to common belief, the research also found that diabetes may not be directly associated with small vessel ischemic disease (SVID).

“Diabetes duration correlated primarily with brain atrophy,” said lead author R. Nick Bryan, MD, PhD, of the Perleman School of Medicine at the University of Pennsylvania in Philadelphia, in a press release. “Stated another way, our results suggested that, for every 10 years of diabetes duration, the brain of a patient with diabetes looks approximately two years older than that of a non-diabetic person in terms of gray matter volume.”

Because the presumed etiologic relationship between diabetes and vascular disease is well-established, many hypothesize that diabetes is a risk factor for SVID. Little research has been done on whether measures of disease severity are associated with indicators of brain pathology identified on MRI, which is where the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial comes into play.

Bryan and colleagues used MRI in their ACCORD trial to investigate the association between severity and duration of type 2 mellitus and brain structure in 614 patients across four centers.

The study group’s mean duration of disease was 9.9 years. The researchers focused on the potential for inverse correlation between more severe diabetes and brain volume and a positive correlation between disease severity and ischemic lesion volumes.

The mean volume of abnormal tissue was 2.5 cm2 and was mostly in the white matter at 81 percent. The study’s results revealed that a longer diabetes duration was associated with brain volume loss, especially in the gray matter. The researchers found no association between diabetes characteristics and small vessel ischemic disease in the brain.

Fasting plasma glucose was inversely correlated with ischemic lesion volume, but hemoglobin A1c was not associated with any MRI measure.

“Our study results provided additional support for the position that, despite common clinical perception, diabetes is not directly related to SVID,” wrote Bryan and colleagues. “Age, hypertension and, to a lesser extent, smoking remain the strongest predictors of SVID,” they concluded.