Diabetes mellitus type 2 (DM2) is a common chronic metabolic disorder that affects 4.1% of the Dutch population. In addition to vascular disease, DM2 is associated with structural brain changes visible on MRI, accelerated cognitive decline, and dementia in older individuals. The exact pathophysiological mechanisms underlying cognitive decrements in DM2 still remain to be elucidated. The 'metabolic syndrome' (MetS), defined as a cluster of cardiovascular risk factors (including obesity, hypertension, and dyslipidemia) is often considered a prediabetic condition. Individuals with MetS display similar cognitive decrements as do DM2 patients, but do not share the severity of brain injury. It has been indicated that in prediabetic MetS, cognitive problems precede structural brain changes, and that MetS and DM2 affect the brain through a shared mechanism in which vascular co-morbidity is essential.