Most people who eat a western diet eat too much and too often which causes a chronic increase in the insulin levels in our blood and is the leading cause of diabetes Type II (adult onset diabetes).
The good news is that studies have proven that fasting intermittently dramatically reduces our insulin levels and therefore we can prevent this from happening.
A study in the Journal of Applied Physiology (2005; Vol 99) took a group of 8 men who fasted for 20 hours at a time on alternating days and measured their insulin levels and insulin sensitivity (ability to regulate blood sugar). It showed that their insulin sensitivity had significantly improved during their very first fast.
Another study on a group of 6 men (American Journal of Physiology 1993) asked them to fast for 72 hours and their blood insulin levels were measured throughout the fast.