Re: New study shows dietary fat doesn't cause problems
"I thought diabetes was always associated with carbs, not fat."
Type 2 diabetes is still rather a mystery. But certainly being overweight or obese, and lack of serious regular exercise are correlated with increased rates. It's got a generic component. (Of course you will always find someone who is obese, does no exercise, smokes 80 a day and lives to 90 but that is the tail of a distribution.)
What I've gathered (it's not really my area of expertise) : High blood glucose drives the production of insulin as a signaling hormone in an attempt to reduce the damaging effect of high levels. If, the mechanisms driven by insulin for some reasons fail to bring it down then a vicious circle of greater and great demands for insulin ensues. This can eventually destroy the insulin producing cells.
The mechanisms that reduce insulin include muscle/liver absorbing glucose and converting it to it's storage form glycogen. This is where the exercise comes in Exercise at first uses stored glucose leaving the exercised muscles/liver able to absorb more. If you don't exercise and esp. if your muscle mass is low the very mechanism that normally reduces blood glucose is blocked. If you have a lot of stored fat it can fueling metabolism again allowing blood glucose to increase over normal. This all is really a rate effect. Slow glucose release from the gut allows other (slower) mechanisms to absorb the glucose, for example, converting glucose to fat.
There are many mechanisms/enzymes/signaling pathways involved in this so it's no suprise that individuals and their genetics vary greatly. There are a number of refinements to all this, for example, exercise greatly increases the ability and extent of muscle to absorb glucose rapidly and also mobilise fat . Complex subject.