Introduction: Patients with periodontitis are significantly more likely to have undetected diabetes mellitus (DM). Self‑monitoring devices like glucometers provide a simple method for rapid monitoring of the glucose level in blood by utilizing a blood sample from the finger, but this method requires puncturing to obtain blood. Bleeding from the gingival sulcus, obtained during oral hygiene examination, can be utilized for screening DM patients. Therefore, this study was performed with the aim of determining the efficacy of gingival crevicular blood as a non-invasive screening method for DM patients, as well as correlating and comparing gingival crevicular blood glucose (GCBG) levels with finger capillary blood glucose (FCBG) and fasting blood glucose (FBG) among non-diabetic and diabetic group patients.Methods: In this cross-sectional comparative study, a total of 120 participants having moderate to severe gingivitis/periodontitis with an age range of 40 to 65 years were divided into two groups on the basis of FBG range taken from an antecubital vein: non-diabetic (≤126, n=60) and diabetic (≥126, n=60) groups. Blood oozing during the routine periodontal examination from the periodontal pocket was recorded using a test strip of a glucose self-monitoring device (AccuSure®Simple) as GCBG. Concomitantly FCBG was collected from the fingertip. These three parameters were statistically analyzed using the Student's t-test and the one-way ANOVA test and correlated with Pearson's correlation coefficient for both groups.Results: The mean and standard deviation for the three parameters GCBG, FBG, and FCBG were 93.78±12.03, 89.98±13.22, and 93.08±15.56, respectively, for the non-diabetic group and 154.52±45.05, 159±47.00, and 162.23±50.60 subsequently for the diabetic group. Comparing glucose level parameters among the non-diabetic and diabetic groups suggests a significant difference with the p-value <0.001*(inter-group). ANOVA test was done for both groups suggesting no significant difference among these three methods of measuring blood glucose level, where the p-value found was 0.272 for the non-diabetic and 0.665 for the diabetic group (intra-group comparison). Pearson's correlation values suggested a good positive correlation for the non-diabetic group, with parameters GCBG and FBG (r=0.864), GCBG and FCBG (r=0.936), and FBG and FCBG (r=0.837). The diabetic group's Pearson's correlation suggested a highly significant positive correlation between three different methods in which GCBG and FBG (r=0.978), GCBG and FBG (r=0.977), and FBG and FCBG (r= 0.982).Conclusion: Blood oozing from the periodontal pocket during routine oral hygiene examination can be utilized by dental healthcare professionals to screen pre-diabetic patients which can be used as a simple and less invasive method for DM patients.