PROC GLIMMIX's option: lsmeans group / ilink diff;

proc glimmix data=asdf METHOD=RSPL;

class CAMPUS_14 subgroup;

model y=x1 x2 x3 subgroup

/dist=binomial link=logit s ddfm=kr;

lsmeans group / ilink diff;

ods output  ModelInfo=x1var1 ParameterEstimates=x2var1 CovParms=x3var1

Diffs=DIF_RESULT1 LSMeans=LS1;

run;