Objectives: To quantify the frequency of abnormal plasma glucose readings among dental patients in practices in The Dental Practice-Based Research Network (DPBRN; www.DentalPBRN.org). Methods: Trained DPBRN practitioner-investigators recruited consecutive patients who presented to their practices for any treatment that required a routine examination. Eligible subjects were 19 years of age or older who had at least one American Diabetes Association-defined risk factor for diabetes mellitus (DM) or a standing diagnosis of DM or pre-DM. Patients were enrolled in each participating practice until 15 qualified and consented. We measured random (i.e., fasting not required) plasma glucose in standardized fashion using a FreeStyle Freedom Lite meter (Abbott Diabetes Care), commonly available in retail stores. Readings <50mg/dL or >300mg/dL triggered re-testing. Patients with glucose >200mg/dL were given letters of referral for follow-up with medical services. Results: We enrolled 498 subjects in 28 dental practices in the 5 main regions of DPBRN (Alabama/Mississippi; Florida/Georgia; Minnesota; Permanente Dental Associates in cooperation with Kaiser Permanente NW Research Foundation; and Scandinavia). Of these, 491 (98%) patients consented to be tested. There were 51 patients (12.2%) previously diagnosed with DM and 24 (5.7%) with pre-DM. Plasma glucose reading ranged from 50 to 465mg/dL. Among all tested patients, 31% had plasma glucose readings outside the normal range; of these, 28 patients (6.7%) were hypoglycemic (glu<80mg/dl) and 101 (24.4%) were hyperglycemic (glu>120mg/dL); in 9 patients (7 with previously diagnosed DM), plasma glucose was >200mg/dL. Conclusions: Random plasma glucose measurement in dental practice can provide clinically relevant information. Our results offer a view into the potential public health benefits of glucose testing in dental practice for patients with DM or at risk for DM.