This is probably the most recent, well-cited article on the topic. The authors looked at the effects of saccharin in mice, and were able to determine that there was a significant elevation in blood-glucose level for the mice that were fed saccharin instead of actual glucose over the course of nine weeks. This suggests a mechanism for previous findings that suggest artificial sweeteners cause insulin insensitivity, weight gain, type II diabetes, et cetera. The difference between the two diets went away when both groups were raised with antibiotics, strongly suggesting the underlying cause was gut microbiota. They also found evidence that the saccharin diet led to changes in gut microbiome composition:
In agreement with the experiments with antibiotics, next generation sequencing of the microbiome indicated that mice drinking saccharin had distinct compositions from controls. This distinct microbiome was characterized by enrichment of taxa belonging to the Bacteroides genus or the Clostridiales order, with under-representation of Lactobacilli and other members of the Clostridiales. Several of the bacterial taxa that changed following saccharin consumption were previously associated with type 2 diabetes in humans.
Keep in mind that everyone has different gut flora, so in general these impacts will vary from person to person, which is why the effect is inconsistent, as with obesity and type II diabetes in general. I can't say for certain that these results would directly transfer into humans, but since the bacteria are the same, it's unreasonable to assume they wouldn't. Less clear is whether this effect transfers to other sweeteners; the paper includes a table showing a number of studies pertaining to a diversity of chemicals, some of which found an effect, and some of which didn't.
Non-professionally, my advice would be to avoid artificial sweeteners, and ideally all liquid candy. Some people find that drinking normal, sugary soda produces a state of lethargy, and I'm pretty sure this is a result of the long-term exposure to sucralose. It's sort of a trap!