This directed case study is designed to help students integrate biochemical and physiological concepts with clinical aspects of disease. The case tells the story of a little girl who experiences diabetic ketoacidosis and is diagnosed with type 1 diabetes mellitus (T1DM). The story is based on an actual patient and the presented data are authentic. The case can be delivered as an individual assignment by using the case study handout or displayed in class with optional role play by using the PowerPoint presentation (see Supplemental Materials).  Both versions of the case cover the same basic content, but the questions are somewhat different. Upon successful completion of the case, students should understand the basics of metabolic acidosis in T1DM, differences between T1DM and T2DM, and the behavior of the blood buffer equilibrium in response to physiological change. The case was originally written for an intermediate biochemistry course, but it could also be used in a physiology or an advanced biology course.