Gaia Data Release 2 (DR2; April 25, 2018) provides astrometric and photometric data for more than a billion stars - among them many AGB stars. As part of DR2 the light curves of several hundreds of thousand variable stars, including many long-period variable (LPV) candidates, are made available. The publication of the light curves and LPV-specific attributes in addition to the standard DR2 products offers a unique opportunity to study AGB stars. In this contribution, we present the first results for AGB stars based on the analysis of the Gaia data performed after their release. As an immediate result of the Gaia DR2 LPV database we introduce a new photometric index capable of efficiently distinguishing AGB stars of different masses and chemical properties.