The article's title is appropriately opaque: Sex differences in transgenerational alterations of growth and metabolism in progeny (F2) of female offspring (F1) of rats fed a low protein diet during pregnancy and lactation. But the press story has a very misleading title, Your Type 2 Diabetes Risk Influenced by Grandma's Diet; A bit premature. The authors are discussing their rats, not your grandmother.
It's clear that rodent research is of vital importance in understanding human disease. For instance, many years ago, pancreas transplants from non-diabetic rodents to identical siblings (who were made diabetic by nasty chemicals that researchers use) documented that the transplanted pancreas were able to control blood sugar levels perfectly in the recipients. Of course, in identical twins (whether human or rat), the risk of rejection of the transplant is not an issue. And the point was crucial to understand before undertaking human transplants: transplanted islet cells can indeed release insulin in appropriate amounts to control blood sugar levels.
So, "rat research" will always be important to people with diabetes. Just read the media's version of the stories with skepticism (and read the scientific abstracts or full publications for more details).