If I stop simvastatin for a few weeks to see if it could be affecting my blood sugar level, should there be any problem? My cholesterol is only 175.

Minor glucose effect. Simvastatin can have a minor effect on increasing blood sugar, but it is easy to correct with your diabetes medication. Allowing your cholesterol to increase in the mean time is a mistake. The longer you allow it to be elevated, the more damage it can do.