tl; dr: A mouse study (corroborated by in vitro experiments with human liver tissue) found that a liver signaling protein, ChREBP, is activated by fructose cons

tl; dr: A mouse study (corroborated by in vitro experiments with human liver tissue) found that a liver signaling protein, ChREBP, is activated by fructose consumption and causes the liver to produce glucose in a way that isn't shut down by high insulin levels. IMO this is not so much a "new theory" as an insight into the behavior of a particular pathway that would be part of a theory.