Objective. The present study aimed to compare variations in quantified tumor necrosis factor-alpha (TNF-α) levels in patients with periodontitis stage 2 grade B (POD2B) and/or type 2 diabetes (T2D) and to identify any relationships between this cytokine and these diseases. Methods. Levels of the cytokine TNF-α in gingival crevicular fluid in patients with POD2B and/or T2D were evaluated. A total of 160 subjects were distributed into four groups: those with POD2B (n=44); those with T2D (n=37); those with POD2B/T2D (n=40); and healthy subjects (n=39). Glycosylated hemoglobin (HbA1c) and blood glucose (BG) levels were quantified in each subject. Data were collected on body mass index (BMI), loss of insertion (LI), and probe depth (PD). Gingival crevicular fluid samples were collected from the most acutely affected periodontal pocket and gingival sulcus in each subject, and TNF-α was quantified by multiplex analysis. Results. Kruskal Wallis tests was used to identify differences in TNF-α levels, LI, PD, BMI, BG, and HbA1c by group. Differences (p<0.001) were found for LI, PD, BG, and HbA1c. A Spearman test was used to calculate possible correlations between TNF-α levels and LI or PD identified a weak but significant negative correlation of TNF-α with LI (Rho=-0199; p=0.012), and a moderately positive correlation of LI with PD (Rho=0.509; p < 0.001). Conclusions. No variation was found between TNF-α levels and the presence of POD2B, POD2B/T2D, or T2D, suggesting the absence of any direct relationship between progression of these diseases and TNF-α levels. However, a correlation was present between low TNF-α concentrations and greater LI.