The number of patients with diabetes and diabetes-related complications is increasing. Rapid and accurate diagnosis is key to efficiently providing the appropriate level of care for patients with diabetes. When faced with a hyperglycemic patient (ie, blood glucose level > 250 mg/dL), the prevailing attitude among health care providers is to "think worst first," and common clinical practice is to perform an evaluation for diabetic ketoacidosis (DKA). Traditionally, diagnosing DKA in accordance with the American Diabetes Association guidelines requires performing ≥ 2 (possibly 3) tests to obtain measurements for blood glucose, serum bicarbonate, serum pH, and serum anion gap levels, as well as measurements of either urine or serum ketone bodies. Recently, commercial point-of-care β-hydroxybutyrate measurement devices have become readily accessible and less expensive. These devices offer the potential to simplify clinicians' diagnostic approach to hyperglycemic patients. In this evidence-based literature review, we describe the use of point-of-care β-hydroxybutyrate testing for diagnosing DKA, and discuss its limitations in determining DKA severity.