Diabetic patients are at increased risk for stroke, but little is known about the presence of other brain lesions. We studied the association of magnetic resonance imaging-detected brain lesions to diabetes in 1,252 individuals aged 65-75 years who were randomly selected from eight European population registries or defined working populations. All scans were centrally read for brain abnormalities, including infarcts, white matter lesions, and atrophy. We used a three-point scale to rate periventricular white matter lesions, and the volume of subcortical lesions was calculated according to their number and size. Subjective grading of cortical atrophy by lobe and summation of the lobar grades resulted in a total cortical atrophy score. The mean of three linear measurements of the ventricular diameter relative to the intracranial cavity defined the severity of subcortical atrophy. After adjustment for possible confounders, diabetes was associated with cortical brain atrophy but not with any focal brain lesions or subcortical atrophy. There was a strong interaction of diabetes and hypertension, such that the association between diabetes and cortical atrophy existed only in hypertensive but not in normotensive participants. Cognitive and pathological data are needed to determine the clinical significance of these findings as well as to understand the mechanisms underlying these associations. Diabetes 53:687-692, 2004 D iabetes is a metabolic disorder that affects many systems in the body. Nephropathy, retinopathy, peripheral neuropathy, and cardiac disease are major complications in the advanced stage of the disorder (1). Although it is known that diabetic patients are at increased risk for stroke (2), little is known about the risk for other brain pathology, such as that associated with neurodegeneration or small vessel disease. Previous radiological studies of patients with diabetes were based on highly selective groups of individuals referred to computed tomography or magnetic resonance imaging (MRI) neuroimaging (3-17). Only a few population-based studies assessed the association of diabetes-as one of many cardiovascular disease (CVD) risk factors-to only one specific type of brain lesion (18 -22). The reported results are inconsistent. Only 6 (5,6,8,11,16, 20) of 19 investigations (3-22) found diabetes to be a risk factor for small vessel disease-related brain abnormalities, including white matter lesions or lacunes. Three studies found associations with cerebral atrophy (3,7,21). Interactive effects between diabetes and other major vascular risk factors, particularly arterial hypertension, have been implicated for the development of diabetes-related complications (23). The importance of such interactions for the development of brain abnormalities in diabetic patients is unclear. We hypothesized that diabetes is associated with a variety of focal and diffuse cerebral abnormalities and that there exist interactive effects between diabetes and other major vascular risk factors on the occurrence of brain lesions....