The hormone resistin links obesity to diabetes[1]
Excerpt:
Type 2 diabetes...is strongly associated with obesity; however, the mechanism by which increased adiposity causes insulin resistance is unclear. Here we show that adipocytes secrete a unique signalling molecule...increased in diet-induced and genetic forms of obesity.
Pigment Epithelium-Derived Factor Contributes to Insulin Resistance in Obesity[2]
Excerpt:
Herein, we show that the noninhibitory serine protease inhibitor, pigment epithelium-derived factor (PEDF), plays a causal role in insulin resistance. Adipocyte PEDF expression and serum levels are elevated in several rodent models of obesity and reduced upon weight loss and insulin sensitization.
[0] http://diabetes.diabetesjournals.org/content/43/11/1271.shor...
[1] http://www.nature.com/nature/journal/v409/n6818/full/409307a...
[2] http://www.sciencedirect.com/science/article/pii/S1550413109...
Vast majority is not 100%. As I replied elsewhere, I was reacting to the laziness of the statement more than trying to assert it is not generally the case.
> I'm curious how you think most diagnosed cases of hypertension and Type 2 Diabetes are caused, then.
That is a good, unanswered question. Along with why people who have never been overweight in their life also develop hypertension and Type 2 diabetes and why so many obese people never do. There is certainly a correlation, but there is no causal link as yet to anything in particular.