Aspartame is pretty gross stuff, what with its awful taste and hordes of people who get terrible reactions from consuming it, but that’s not what we’re interested in today. Luckily, there is a good amount of research explaining what, if any, effect aspartame has on insulin secretion.
One study found that protein produced a significant insulin response, while aspartame had no effect on insulin levels.
Another also found that aspartame had no effect on the insulin response in humans, whether alone or combined with carbohydrates.
Another earlier study (full PDF) examined the effects of aspartame on prolactin, cortisol, growth hormone, insulin, and blood glucose levels and found it had none. The authors used the same amount of aspartame you’d find in a standard artificially-sweetened drink but were unable to record any significant hormonal alterations.
A study of forty-eight healthy volunteers found no evidence that aspartame has an effect on insulin levels.
Overall, the evidence seems to suggest little, if any, effect on insulin secretion as a result of tasting or consuming aspartame.