The present invention provides a portable blood sugar measuring device comprising a tape unit for winding a test tape forward in sections, a detection unit for detecting measured values on the sections of tape to which body fluid has been applied, and a housing to hold the tape unit and detection unit. The tape unit and/or the detection unit can be deflected relative to the housing from an operating position against a flexible restoring element when subjected to a shock load. Also disclosed is a novel cover having open and closed positions. The cover is positioned at an opening of the housing through which the receiving site of the tape unit protrudes. The cover thus protects the receiving site from external effects when the cover is in the closed position. Similarly, the receiving site is accessible to apply body fluid thereto when the cover is in the open position.