The theory expressed by Peter Attia is that constant bombardment by high levels of glucose can cause cells to become insulin resistant (diabetes) which causes obesity, heart diseaseand many other western diseases. It basically means too much sugar is bad and that too much sugar through out your entire life can kill.
I found this really good 15 min ted talk on the the causes of diabetes in modern society.
Source:
Here is a summary in case you want to check out more from Peter Attia.
"Peter Attia: What if we're wrong about diabetes?"
Published on Jun 25, 2013
As a young ER doctor, Peter Attia felt contempt for a patient with diabetes. She was overweight, he thought, and thus responsible for the fact that she needed a foot amputation. But years later, Attia received an unpleasant medical surprise that led him to wonder: is our understanding of diabetes right? Could the precursors to diabetes cause obesity, and not the other way around? A look at how assumptions may be leading us to wage the wrong medical war.