Hydrolyzes UDP-glucose to glucose 1-phosphate and UMP and ADP-ribose to ribose 5-phosphate and AMP. The physiological substrate is probably UDP-glucose. Poor activity on other substrates such as ADP-glucose, CDP-glucose, GDP-glucose and GDP-mannose (By similarity). UDP-sugar + H2O = UMP + alpha-D-aldose 1-phosphate. Homodimer. Belongs to the Nudix hydrolase family.