Hi
@IronLioness,
I am convinced that based on the research that stress as well of lack of sleep increases insulin resistance, which when it becomes chronic can lead to the onset of T2.
One specific study (I am not really sure I can find the link anymore) showed that women who worked 45 hrs (instead of the regular 40 hrs) per weak, had a 67% increased chance of developing T2. Another study prevented young men from sleeping (I don't quite remember, if they slept little or not at all) and found that they became for insulin-resistant.
As others, like
@JoKalsbeek and
@Alison Campbell, above have pointed out, it probably has to do with increased stress hormones, especially cortisol.
We probably can't say how important the role of stress is in explaining the onset of T2 (as compared to diet for example or maybe, as some newer research seems to suggest, the number of adipose cells we are equipped with), but it does seem to play a role.