Diabetes mellitus and progression of vascular brain lesions and brain atrophy in patients with symptomatic atherosclerotic disease. The SMART-MR study.

AIM: Diabetes mellitus (DM) is associated with brain atrophy and vascular brain lesions. Cardiovascular disease is a key determinant in this association. We assessed whether DM increased the rate of progression of brain atrophy, vascular brain lesions, and cognitive decline in patients with symptomatic atherosclerotic disease.
METHODS: In 663 patients (58±10years) from the SMART-MR study (n=89 with DM), 1.5T MRI and neuropsychological examination were performed at baseline and after 3.9±0.4years follow-up.
RESULTS: Repeated measures ANCOVA (adjusted for age, sex, and vascular risk factors) showed that patients with DM had smaller total brain volume (mean differences as percentage of intracranial volume (ICV) [95% CI]: -1.36% [-1.81; -0.91]), smaller gray matter volume (-1.23% [-1.85; -0.61]), larger ventricular volume (0.32% [0.14; 0.49]), and larger white matter lesion volume (0.31% [0.09; 0.53]) than patients without DM. Patients with DM had accelerated increase in ventricular volume over time compared with patients without DM (mean differences ventricular volume as percentage of ICV: 0.32% [0.25; 0.39] vs. 0.17% [0.15; 0.19]; p-interaction DM×time<0.01). Poisson regression showed that patients with DM had an increased risk for incident brain infarcts (relative risk [95% CI]: 1.62 [1.04; 2.53]). Patients with and without DM had similar performance on cognition.
CONCLUSIONS: DM on top of existing symptomatic atherosclerotic disease is associated with increased brain atrophy and vascular brain lesion load that proceed at a slightly higher rate than in patients without DM.