<i>Background/Aims:</i> The present study examined the relationship between microvascular complications and cognitive decline and the development of structural brain abnormalities over a period of 4 years in patients with type 2 diabetes mellitus (T2DM). <i>Methods:</i> Sixty-eight elderly patients with T2DM had 2 cognitive assessments with a 4-year interval. Two MRI scans, performed at the same time as the cognitive assessments, were available from 55 patients. Changes in cognitive performance over time were expressed as a regression-based index (RBI). Automated volumetric measurements of total brain, lateral ventricles and white matter hyperintensities were performed. The relationship between baseline microvascular complications [diabetic retinopathy, peripheral neuropathy or albuminuria (micro- or macroalbuminuria)] and cognition and brain volumes was examined with linear regression analyses adjusted for age and sex (for cognition also for IQ). <i>Results:</i> At baseline, diabetic retinopathy was present in 18% of patients, peripheral neuropathy in 36%, albuminuria in 15%. Retinopathy or neuropathy were not significantly associated with baseline cognition or brain volumes, or changes in these measures over time. Albuminuria was associated with a lower composite RBI score, indicating accelerated cognitive decline (adjusted mean difference between patients with or without albuminuria: –0.58, 95% CI –0.85 to –0.31, p < 0.001). <i>Conclusion: </i>Albuminuria predicted accelerated cognitive decline in patients with T2DM, but other microvascular complications were unrelated to accelerated cognitive decline or brain MRI abnormalities.