There is pretty compelling evidence that obesity (particularly belly fat) is the main trigger for T2 diabetes - though you have to carry the genetic susceptibility (similar to cancer and smokers; everyone knows of a chain-smoking relative who lived to 99, but didn't happen to have the genetic susceptibility).
This article sets out some current thinking on the causal link:
http://www.ehow.com/how-does_4923548_ob ... betes.html
In particular, this paragraph explaining one of the mechanisms is the clearest explanation about how insulin resistance develops that I've come across.
(and I think 'overnutrition' can be said to imply overeating and eventually obesity)
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The endoplasmic reticulum (ER) is a specialized membrane, inside the cell, that synthesizes proteins and processes blood fats. Overnutrition is a state where the body has more calories and fat that it can process at one time. When the body enters a state of overnutrition, this puts stress on the ER, causing it to signal the insulin receptors to stop responding to insulin. Temporarily reducing insulin receptivity allows the ER to catch up with its workload. If the body repeatedly enters a state of overnutrition, the ER continually signals the cells to dampen their insulin receptors. Over time, the body is no longer able to respond to insulin properly.
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The explanation about Resistin and how it was an evolutionary mechanism to help us survive famines is also interesting - another obesity-related cause.
I guess once a diabetic you'll always have the *propensity* to (re-)develop it, but many people find that Diet Exercise and WeightLoss make all the symptoms go away (including being able to pass the usual diagnostic tests) - particularly if the D, E & WL program is started as soon as possible after an early diagnosis.
For how long? Who knows; but as experience grows, it's looking to be years and maybe even decades - I'm certainly optimistic!
mark