In an experiment done by the TV show “Trust Me I’m A Doctor”, it was found that eating cold pasta reduced the rise in blood sugar after a meal, and eating reheated pasta gave an even lower rise in blood sugar! The theory is that this effect is because the process of cooling and reheating changes the starch in pasta into “resistant starch”, which is harder for our enzymes to digest and acts more like dietary fibre. Sadly, this was a fairly small study of only 10 people. It is also important to note that while reheated pasta might be slightly healthier, the difference is relatively minimal. It would probably be best to just eat vegetables instead! Check out courgette pasta if you don’t already know about it!
There aren’t many papers on the subject, but here’s one for further reading http://www.ncbi.nlm.nih.gov/pubmed/19562607