How to draw exactly 1 pixel width sloped line ?

I’m not sure, that it is a driver bug or I forgot to set something in the API. When I render a sloped line near 45 deg eg. 50 or 40 deg on different NVIDIA cards, the line width is always looks like more than 1 pixel. Maybe it is better for multisample mode, but without multisample for example drawing a circle from line segments looks wrong. In OpenGL it is OK also on AMD and Intel it is OK.
Could somebody help me, please ?