The invention concerns a base part for a medication delivery device. The base part is during use fastened to a patients skin and connected to a cannula part which cannula part is positioned at least partly subcutaneous. The base part is also connected to a sensor unit which can detect one or more components e.g. glucose content in the patients blood. The base part comprises fastening means (15) which fastening means (15) releasably attach the reservoir/delivery part to the base part during use and a first fluid path or means corresponding to a first fluid path from a reservoir permitting a flow of fluid between the reservoir/delivery part and the base part when the reservoir/delivery part is attached to the base part, the first fluid path comprises means (17) for interrupting the fluid flow when the detachable reservoir/delivery part is not attached to the base part (1) and opening the fluid path (19) when the delivery part is attached to the base part (1). The base part (1) also comprises a lower mounting surface (2) and one or more openings (12A, 12C) through which two or more subcutaneous units (7,70) in the form of at least one cannula and at least one sensor part or at least two cannulas extend and it comprises a second fluid path permitting a flow of fluid from the outlet of the first fluid path to an inlet of a subcutaneously positioned cannula (22, 22a, 22b) during use, and a signal path is provided from the reservoir/delivery part to a sensor contact part. The base part is characterized in that the second fluid path is in fluid connection with an end opening of a subcutaneously positioned cannula during use.Linvention porte sur une partie de base pour un dispositif dadministration de médicament. La partie de base est fixée à la peau dun patient pendant son utilisation et elle est reliée à une partie canule, laquelle partie canule est positionnée au moins en partie sous la peau. La partie de base est aussi reliée à une unité de détection qui peut détecter un
