Playing a line in QGA from a QGD for White I was playing the other day a Queens gambit game, but it seems that my opponent had a very good prep against players like me who play with White like:
[FEN &quot;&quot;]
1.d4 d5 2.c4 e6 3.Nc3 dxc4

I usually go for a setup with Nf3, e3 (my bishop is locked and I fianchetto it on b2 later in the game). My line against QGA goes like this
[FEN &quot;&quot;]
1. d4 d5 2. c4 dxc4 3. Nf3 Nf6 4. e3 e6 5. Bxc4 c5 6. O-O a6 7.
b3 7... Nc6 8. Bb2 cxd4 9. Nxd4 Bd7 10. Nf3 Be7 11. Nbd2 O-O 12. Rc1 Rc8 13. Qe2 Qa5 14. a3 
Rfd8 15. b4 Qh5 16. Nb3  *

Note that my opponent tricks me into playing a QGA with my knight on c3. It really annoys me a lot. I looked at some lines like this:
[FEN &quot;&quot;]
1.d4 d5 2.c4 e6 3.Nc3 dxc4 4. e3 a6 5. a4 (5. Bxc4 b5 6. Be2 Bb7 7. Bf3 ( 7. Nf3 Nf6 8. O-O 
Nbd7 9. b3 c5 10. Bb2 Rc8 11. Rc1 Be7 12. dxc5 Bxc5 13. a4 b4 14. Nb1 O-O 15. Nbd2 Nd5 16. 
Nc4 Be7 ) Bxf3 8. Nxf3 Nf6 9.O-O c5) 5... Bb4 6. Bxc4 Nf6 7. Nf3 b6 8. O-O Bb7 9. Qe2 O-O 
10. Bd3 c5 11. dxc5 Bxc5 12. e4 
Nbd7 13. Bf4 Nh5 14. Be3

I noticed that in the 5. a4 line Black is fine and has some initiative on my kingside which I also disliked. And in the 5. Bxc4 line I feel more comfortable playing it. The 5. Bxc4 b5 6. Be2 Bb7 7. Bf3 variation is a bit dry, and the 5. Bxc4 b5 6. Be2 Bb7 7. Nf3 variation I like it more  but the engine doesn't like it much!
The other option is to play 4. e4, which has a lot of theory in QGA and I also tried to avoid it by playing the other mainline in the QGA with Nf3 and e3. Playing the positions with 4.e4 are really hard imo. I tried to play e4 variation in QGA for 2 years and felt uncomfortable. I prefer to play the other system with Nf3 and e3. I would really appreciate some feedback on how to play a QGA the way that I like with Nf3 and e3 if black plays 1.d4 d5 2.c4 e6 3.Nc3 dxc4. I just don't wanna go to e4 variations unless you have a very easy reference that I can read about it. Thanks!
After 1.d4 d5 2.c4 dxc4 3.Nc3, 3...e6 is a pretty weak response due to 4.e4!. In your example, you can reach that exact position, where you basically take as much space in the center as you want for free. Sure it's not the type of position you're probably used to, but that's only because this one is actually a lot better and Black rarely allows you to reach it.
In other words, you'll succesfully achieve all the goals in the Queen's Gambit. You'll retake the c4 pawn and get a massive center with your e4+d4 formation all of this while keeping your king safe and your pieces developped!
Furthermore, an e5 reaction is one of the main resources Black has against our d4+e4 formation, so e6 was pretty much a lost tempo