Clinical practice guidelines constitute one of the most important sources of information and education for physicians. Therefore, establishing rules to develop and appraise such guidelines properly is of increasing importance. This task is served by the AGREE (Appraisal of Guidelines Research and Evaluation) instrument, a questionnaire, which, according to its authors, allows reproducible assessment of guideline quality. The aim of this paper is to allow readers familiarize themselves with such rules of guidelines appraisal. In order to achieve this purpose, we present the actual application of the AGREE instrument using as an example recently published document on postmeal hyperglycemia issued by the International Diabetes Federation.