Catalysis of the reaction: GDP-6-deoxy-D-mannose + NAD(P)+ = GDP-4-dehydro-6-deoxy-D-mannose + NAD(P)H + H+.
Source:EC:1.1.1.281
Comment
Note that this enzyme differs from EC:1.1.1.187, GDP-4-dehydro-D-rhamnose reductase, in that the only product formed is GDP-D-rhamnose (GDP-6-deoxy-D-mannose).