Aims The aim of the present study was to evaluate whether there was an inflammation-mediated link between Alzheimer's disease (AD) and type 2 diabetes mellitus (DM) status. Methods An age-matched control group and patient groups designated as AD without treatment (AD); AD under cholinesterase inhibitors (AD-CEI); DM without treatment (DM); DM under oral antidiabetic agents (DM-OAD); AD under treatment, who had newly diagnosed DM (AD-CEI+DM); and DM under treatment, who had newly diagnosed probable AD (DM-OAD+AD) were studied. Serum inflammation status was evaluated by the determination of serum C-reactive protein (CRP), tumor necrosis factor-alpha, interleukin (IL)-1β and IL-6 levels. CRP levels were determined by an immunonephelometric method. The others were assayed by enzyme-linked immunosorbent assay methods. Results IL-1β levels were found to be significantly lower in the DM group than in the control group (P