That (0.1mm) is too tight More like 0.25 to 0.4mm, and towards the high end if you're designing for automatic insertion of parts with bent leads. Usually 0.8mm is okay for most leads except fat diode leads, for which you can use 1.0mm.
Usually 1.3mm holes are specified for 1mm pins (for example on terminal block datasheets), sometimes 1.5mm which is really, really loose. Data sheet recommendations often err on the side of making the holes on the loose side, especially for parts like terminal blocks and relays.
If the leads are flat or square rather than round you can go a bit tighter on the diagonal dimension, assuming a round hole. For really flat leads it's better to specify a slot, of course.
Here are some recommendations (in inches, unfortunately, but 25.4 is fast to key in).
Of course if you're using some kind of special part such as a staked connector or press-fit part, follow the recommendations on the datasheet and pay attention to the tolerances too.