Splenda, even though it is calorie free raises his blood sugar level and keeps it raised. Raw sugar and raw honey, also raise his blood sugar levels, BUT not as long, and his body is able to return to normal blood sugar levels after having a food with raw honey / raw sugar as opposed to the synthetics sugars.
Artificial sweeteners, or sugar substitutes, offer the sweetness of sugar without the calories. Artificial sweeteners are many times sweeter than sugar, so it takes a smaller amount to sweeten foods. This is why foods made with artificial sweeteners may have fewer calories than those made with sugar.
Sugar substitutes don't affect your blood sugar level. In fact, most artificial sweeteners are considered “free foods” — foods containing less than 20 calories and 5 grams or less of carbohydrates — because they don't count as calories or carbohydrates on a diabetes exchange. Remember, however, other ingredients in foods containing artificial sweeteners can still affect your blood sugar level.
Also, be cautious with sugar alcohols — including mannitol, sorbitol and xylitol. Sugar alcohols can increase your blood sugar level. And for some people, sugar alcohols may cause diarrhea.
M. Regina Castro, M.D.
http://www.mayoclinic.com/health/artificial-sweeteners/AN00348