Aim: Study was carried out to evaluate the efficacy of a glucometer for screening diabetes using gingival crevicular blood and to compare the blood glucose levels in the gingival crevicular blood sample and blood sample collected by finger puncture method using glucometers. Subjects and Methods: A total of 24 known diabetic patients who fulfilled the selection criteria were selected after obtaining their informed consent. Samples were collected from two sites, i.e., gingival crevice and fingertip which was measured using a self-monitoring device. Statistical Analysis Used: Karl Pearson correlation. Results: This study revealed the existence of a positive correlation between gingival crevicular blood and capillary blood glucose level (r = 0.826), and gingival blood glucose level estimates 68.2% of capillary blood glucose level. Hence, based on the observations of the study using gingival crevicular blood glucose level, capillary blood glucose level may be estimated based on the following regression equation. Capillary blood glucose = 84.66 + 0.77x gingival crevicular blood glucose level. Conclusions: The intraoral sampling technique is safer, convenient, and cost-effective for the dental practitioner as the sample can be obtained during the routine periodontal examination. It can be concluded that with the regression equation based on the gingival crevicular blood glucose level, capillary blood glucose can be estimated.