Background: Diabetes mellitus (DM) is one of the most important risk factors for destructive periodontitis. It is possible that gingival crevicular blood from routine periodontal probing may be a source of blood for glucose measurements. Aim: To compare gingival crevicular blood and finger stick blood glucose measurements using a self-monitoring device. Materials and Method: 30 patients with periodontitis and positive bleeding on probing were chosen. Blood samples of two sites were analyzed using a glucose self-monitoring device. Glucose levels in gingival crevicular blood (GCBG) and capillary finger prickblood (CFBG) samples were analyzed using the same device. The following clinical periodontal parameters were recorded: probing depth, gingival bleeding index, clinical attachment loss and periodontal disease index. The Statistical Analysis was carried out. Results:Sufficiently large GCB volumes provided glucometer readings in all 30 cases (range between60 and 160 mg/dl). The CFB readings ranged between 60 and 166 mg/dl. Karl Pearson’s product–moment correlation coefficient was calculated, which showed a positive correlation between the two measurements (r = 0.592) and p- value (0.001). Conclusion: Gingival crevicular blood can be used for testing blood glucose during periodontal examination in patients with periodontal disease.