An insulated drinking straw and an insulating member for use in drinking hot and cold liquids, such as those consumed from a cup or other container. The insulated drinking straw comprises an inner tubular member and an insulating member disposed around a portion of the periphery of the inner tubular member. The insulating member may be used as a separate device. In one embodiment of the insulating member, the insulating member has an inner shaft, an outer shaft connected to the inner shaft such that an air space is formed between the shafts, and a slot is formed in the insulating member between the inner and outer shafts. In another embodiment of the insulating member, the insulating member has an outer shaft, a compressible insulating material having an inner opening that is attached to an inner wall of the outer shaft, and a slot is formed in the compressible insulating material and outer shaft.