Abstract: A biological sampling/measuring instrument including a first housing including a needle arranged for protrusion therefrom, the needle being adapted to draw therethrough a biological fluid, a reagent disposed in the first housing in fluid communication with the needle, capable of producing an optically-sensible reaction with a biological fluid, and an optical sensor disposed in the first housing adapted to sense the optically-sensible reaction. In one embodiment, the instrument is an elongate instrument suitable for taking and testing small blood samples from a human. The instrument may have a disposable part and a reusable part to which the disposable part connects.