This is how Stevia is Processed in the Body
Carbohydrates are broken down into basic sugars (glucose) and absorbed inside the gut lumen of a small intestine. Using ion channels (like Na+ / K+ pump) and transports ( Na+ / glucose and GLUT2) glucose is moved from small intestine into the bloodstream. 
Stevia glycosides contain glucose molecules but are not broken down (hydrolyzed) in the small intestine, and instead moved intact into large intestine or colon.
Inside colon, gut bacteria digest glycosides and brake off glucose molecules, leaving steviol backbone. [1-3] The free floating glucose molecules are not absorbed but believed to be used by the gut bacteria during digestion. [3,4]
Steviol itself does not create insulin response, hence maintains the fasting state (even when some steviol is absorbed into the blood stream and eventually excreted).
A lot of stevia research revolves around diabetes, cardiovascular and blood sugar regulations. [4,5] So, we looked at parts of information within the studies and compared them to the requirements of our fasting goals.
The normal fasting blood glucose for people is between 3.9 to 7.2 mmol/L, with average of 5.5 mmol/L (or a teaspoon of sugar within 5 Litres of blood volume). 
Stevia produces insulin response when the blood glucose is fairly high (above 8.3 mmol/L) and lowers it. [1,5] During usual fasting blood glucose level (below 5.6 mmol/L ), stevia does not invoke insulin release, and maintains the fasting state.
This means that a large meal filled with carbs will raise our blood sugar levels higher than normal. And, eating stevia will actually help in lowering elevated blood glucose through faster insulin response.
But when we fast, our blood glucose levels are already low and steady, so eating stevia doesn’t invoke insulin.
This is why stevia is a promising diabetes research topic, showing better insulin response and movement of glucose from blood into cells. [1-5]