Decision making regarding fluid volume loading, fluid restriction, or administration of vasoactive drugs may vary among physicians, depending solely upon their clinical experience in the absence of evidence-based measurement. The initial distribution volume of glucose (IDVG) is believed to be clinically relevant as a marker of cardiovascular and fluid management in critically ill patients without a significant modification of glucose metabolism. This book covers all aspects of IDVG measurement, including the basic concept, its relationship with other fluid volumes, and the clinical application of this technique in the intensive care unit based on both the authors’ studies and their clinical experience with more than 4000 IDVG determinations. When the concept of IDVG is properly understood and its measurement is then performed routinely, daily fluid and cardiovascular management in critically ill patients can be improved based on evidence-based measurement.