Background: Early diagnosis and treatment of prediabetes and type 2 diabetes mellitus (T2DM) can prevent future health problems, yet many individuals with these conditions are undiagnosed. This could be due, in part, to primary care physicians' (PCP) screening practices, about which little is known. The objectives of this study were to identify factors that influence PCPs' decisions to screen patients for T2DM and to characterize their interpretation and communication of screening test results to patients. Methods: We conducted semi-structured chart-stimulated recall interviews with 20 University of Michigan Health System (UMHS) primary care physicians. PCPs were asked about their recent decisions to screen or not screen 134 purposively sampled non-diabetic patients who met American Diabetes Association criteria for screening for T2DM. Interviews were audio-recorded, transcribed, and analyzed using qualitative directed content analysis. Data on patient demographic characteristics and comorbidities were abstracted from the electronic health record. Results: The most common reasons PCPs gave for not screening 63 patients for T2DM were knowledge of a previously normal screening test (49%) and a visit for reasons other than a health maintenance examination (48%). The most common reasons PCPs gave for screening 71 patients for T2DM were knowledge of a previously abnormal screening test (49%), and patients' weight (42%) and age (38%). PCPs correctly interpreted 89% of screening test results and communicated 95% of test results to patients. Among 24 patients found to have prediabetes, PCPs usually (58%) recommended weight loss and increased physical activity but never recommended participation in a Diabetes Prevention Program or use of metformin. Conclusions: Previous screening test results, visit types, and patients' weight and age influenced PCPs' decisions to screen for T2DM. When patients were screened, test results were generally correctly interpreted and consistently communicated. Recommendations to patients with prediabetes could better reflect evidence-based strategies to prevent T2DM.