Type 2 diabetes mellitus has been associated with an about 2-fold increase in risk of Alzheimer's disease (AD). Patients with AD have been reported to have reduced insulin sensitivity. It may be hypothesized that, compared to insulin sensitive subjects otherwise similar in general health and body habitus, insulin resistant subjects are more likely to have cerebrospinal fluid (CSF) indicators of incipient AD pathology, abnormalities in CSF peptides related to insulin signaling and glucose homeostasis, and possibly other metabolites that are associated with a risk of AD. The objective of this study is to examine the relation of insulin resistance and the concentrations of CSF biomarkers. The results of this study may be useful in the detection of the subjects who are at risk for cognitive decline and AD.