Validation of HbA1c as a diagnostic marker for diabetes in the critically ill

Diabetes mellitus (DM) is a highly prevalent disease: about one-quarter of patients admitted to hospital is diagnosed with DM, but there are also a large number of patients who are undiagnosed. An acutely ill patient with hyperglycaemia and no history of diabetes may have stress hyperglycaemia or a first manifestation of diabetes, but it is virtually impossible to establish diagnosis based on measurements of glucose. HbA1c is widely used as a marker of glycaemic control and has been proposed and used, but not yet officially accepted, as a diagnostic marker for diabetes. We have tested its usefulness for diagnosing diabetes in the intensive care setting.