A sedentary lifestyle is known to be a major risk factor in the development of Type 2 diabetes, and diseases of the heart and blood vessels.
According to researchers at the Baker IDI Heart and Diabetes Institute in Melbourne, Australia, even short intervals of breaking up sitting time with walking time could be good for prevention and treatment of both conditions.
The study, published in the journal Diabetes Care in January 2013, included 19 overweight or obese adults between the ages of 45 and 65.
They were divided into three groups and performed uninterrupted sitting...

• sitting with 2 minute breaks of light walking every 20 minutes, and
• sitting with 2 minute breaks of moderate walking every 20 minutes.
  

All participants were given a drink containing 75 grams of sugar and 50 grams of fat...

• the group sitting still for 5 hours had the highest blood sugar levels,
• followed by the group who had 2 minute breaks performing light walking, and
• the lowest blood sugar levels were seen in participants performing moderate walking during their breaks.
  

Insulin levels were also highest in the group without breaks and lowest in the group performing moderate level walking, showing the most physically active group had the lowest need for insulin.
From these results it was concluded taking short breaks with physical activity could improve sugar metabolism and prevent heart and blood vessel disease in overweight and obese adults.

• walking for one hour at a slow speed burns around 100 calories per hour.
  
• walking at 3 miles per hour burns approximately 200 calories per hour, and
• walking briskly at 4 miles per hour burns about 300 calories per hour.
  

Besides burning fat, walking also helps your body to build muscles and bones and improves insulin sensitivity, which can help to prevent the development of Type 2 diabetes.
Taking a break every 20 minutes at work would not be practical at most desk jobs, but walking during the breaks one does have would probably be beneficial.
When you're sitting at home at the computer or watching television, why not get up and take a two-minute walking break every 20 minutes? If you're watching commercial television, it would be a great way to escape the commercials.
Take a quick, two-minute walk in the garden and you might not even want to go back inside to watch TV.
See how fast you can walk around the block.
Go for the dust cloth or vacuum cleaner and see how much you can get done during the commercial break.