Sugar prices ruled flat at all levels on Wednesday on routine demand and supply. On Monday 19-20 mills sold 24,000-25,000 bags at Rs 3,100-3,110 of S-grade and Rs 3,100-3,120 of M-grade. Bombay Sugar Merchants Association spot rates: S-grade Rs 3,137-3,212 and M-grade Rs 3,200-3,282. Naka delivery rates: S-grade Rs 3,130-3,200 and M-grade Rs 3,180-3,230.