data one;
  input pair diet1 diet2;
  cards;
1 596 498
2 422 460
3 524 468
4 454 458
5 538 530
6 552 482
7 478 528
8 564 598
9 556 456
;
run;

proc print data=one;
run;

data two; set one;
  difference=diet1-diet2;
run;

proc print data=two;
run;

proc means data=two mean std stderr clm alpha=0.05;
  var difference;
run;