However, the data is scarce and even contradictory. Even less is known about the histological characteristics of the duodenal mucosa in obesity and lean states, but several studies already performed hint for some differences. These differences might influence gut hormones composition and function and play a crucial role in the development of obesity and metabolic syndrome. To our best knowledge, in-vivo, human, real-time cellular level comparison of gastric and duodenal mucosa has never been done. This can be now accomplished with pCLE.