Whilst researching the topic of the negative effects of sedentary behaviour on the body I came across these articles, both by Alex Hutchinson (writing for The Globe and Mail and blogging on Sweat Science), on the ill effect that sitting for long periods of time can have on the body.
The more recent one from Sweat Science, is a good synopsis of how sedentary behaviour, in particular sitting, has an effect on how our bodies handle sugar. The answer, according this Australian study, is not very well. Apparently the test group that sat (as oppose to those who had walking breaks) had a much higher spike in blood sugar levels. So, without getting too technical, insulin, which should be taking care of the blood sugar levels, isn’t doing it’s job. This makes sense when you consider the fact that exercise causes an insulin like effect on the body, causing you to take up sugar out of the blood (that’s why exercise is really handy for people who have diabetes too!)
For more of a background on this subject, check out Alex’s article in the Globe and Mail.