Abstract The prevalence of diabetes in the United States in 2015 was 30.3 million people; which is the equivalent of 9.4% of the population. It is a major contributor to morbidity and mortality. Depression is often underdiagnosed in these patients, which contributes to poor self-management and poor health outcomes. In a large primary-care practice on the East Coast, there is no guideline for depression screening in the diabetic population. Focusing on this specific primary care setting, the research question addressed the underdiagnoses of depression in diabetic patients. The project evaluated the prevalence of depression among patients diagnosed with diabetes by using the U.S. Preventative Services Task Force (USPSTF) depression screening tool called the Patient Depression Questionnaire. The Grove Model for Implementing Evidence-Based Guidelines in Practice Framework was used in systematically integrating the new practice guideline of screening all diabetes patients for depression. The framework involves identifying the practice problem, locating, and collecting the most well-founded evidence, and evaluating the quality of the evidence-based guideline of screening all diabetes patients for depression. To answer the project question, 135 diabetic patients in a primary care outpatient setting completed the Patient Depression Questionnaire. Descriptive statistics was used to describe the sample and determine the frequency of scores throughout the sample of patients. Ranges of scores and percentages were computed using frequency distribution. Of these 135 diabetic patients, 63.7% showed some level of depression ranging from mild to severe, which was undiagnosed prior to the administration of the screening tool. As a result of the project, recommendations were made to the site to implement the use of the depression screening tool as policy.