Objective: The purpose of this study was to determine the level of glycemic control in dental patients with diabetes upon admission to a dental school clinic. Methods and Materials: One hundred patients (mean age: 57.7 years) of the Oral Diagnosis-Admissions Clinic at the University of Minnesota School of Dentistry, Minneapolis, Minnesota, with diabetes mellitus were chosen as subjects. Fasting blood glucose was measured using a portable blood glucose monitoring device as a part of their initial dental examination. Results: Twenty-eight of the 100 patients were found to be hyperglycemic (>= 126 mg/dl; 174.8 ± 40.8 mg/dl; mean ± SEM); 2 patients were found to be hypoglycemic ( 70 mg/dl). Of the 8 patients with type 1 diabetes in the cohort, 3 (37.5%) were very hyperglycemic, with fasting blood glucose levels > 250 mg/dl. Conclusions: This is important information for dental practitioners because patients with diabetes may not be under good glycemic control, and dentists may have to take special precautions before, during, and after treatment. This paper reviews the pathogenesis of diabetes, the detection of patients with undiagnosed or poorly controlled diabetes, and the management of patients with diabetes during dental treatment. Keywords: blood glucose, diabetes, diabetes mellitus, dentistry, infections, hyperglycemia, hypoglycemia, insulin