Given that per the below cite 38 percent of Americans meet one or more of the definitions of diabetes the China number isn't really surprising (but note that I am not certain the China numbe uses the same definition so it may not be completely comparable). I think the number is definitely inflated some, but there is no doubt there is a big problem coming.
FWIW I think it is a virtual certainty that the problem is multifactorial, but one of the more intriguing possibilities is that a significant part of it may be 'epigenetic' (aka Lamarkian) and thus particularly difficult to walk back from an epidemic perspective.