Distinct markers in the blood of people with celiac disease have been detected within a few hours of gluten being consumed. The findings address a longstanding mystery about what drives the adverse reaction to gluten in celiac disease and could lead to a world-first blood test for diagnosing the disease. A potential blood-based test would be a vast improvement on the current approach which requires people to consume gluten for a number of weeks, and even months, for the testing to be accurate.