The gingival crevicular fluid (GCF) and monocytic secretion of prostaglandin E2 (PGE2) and interleukin 1 beta (IL-1 beta) were measured in a group of 39 insulin-dependent diabetes mellitus (IDDM) patients and 64 systemically healthy individuals. Diabetics were divided into Group A (gingivitis or mild periodontal disease) and Group B (moderate or severe periodontal disease). Diabetics had significantly higher GCF levels of both PGE2 and IL-1 beta as compared to non-diabetic controls who were matched with regard to periodontal disease severity (P < 0.00001 and P = 0.0005, respectively). Within the diabetic population, the GCF levels of these inflammatory mediators were almost 2-fold higher in Group B as compared to Group A (P = 0.01, P = 0.006, respectively for GCF-PGE2 and IL-1 beta). Furthermore, diabetics as a group had a significantly higher monocytic PGE2 and IL-1 beta production in response to various concentrations of both Escherichia coli and Prophyromonas gingivalis lipopolysaccharide (LPS) as compared to non-diabetic patients with adult periodontitis (P = 0.0001). LPS dose-response curves demonstrated that monocytes from Group B diabetics produced approximately 3 times more PGE2 than Group A monocytes; however, there was no significant difference in monocytic IL-1 beta secretion within the IDDM patients. The levels of GCF or monocytic mediators did not correlate with age, race, or glycosylated hemoglobin (HbA1C) levels. Our data suggest that the high GCF and monocytic secretion of PGE2 and IL-1 beta in IDDM patients may be a consequence of a systemic response trait and that the presence of Gram-negative infections such as periodontal diseases may interact synergistically to yield high local levels of these mediators and a more severe periodontal condition.