After consulting with some mates who are training to become doctors (hence why from now on, I'm staying as healthy as I can) they tend to use glue in situation were it would be to difficult to stitch, i.e. the chin, elbow etc etc.
Also it it tends to be more safer as it keeps the cut cleaner, and provides a completely waterproof seal.
However it does not mean that you should us the superglue in the house next time you get a cut, the glue used by the doctors is produced to a higher standard than those used to stick two bits of modeling kit together (or indeed my little cousins fingers, long story) i.e there is less impurities in the one used by the docs, than by the ones used at homes.