A wolf in sheep's clothing is an ancient cautionary tale. One form of the saying appears in the Bible, though the story is often accredited to Aesop.

Well here’s a 21st-century version of the fable: Some non-nutritive sweeteners, which promise all the pleasures of sugary flavor without the sugar, are actually hiding their nasty potential.

Research published in the journal Cell looked at the impact of artificial sweeteners on 120 healthy adults over 29 days. It reveals that saccharin and sucralose increase blood sugar levels by triggering changes in the composition and function of gut microbes and the molecules they secrete into your blood.

Fake sweeteners' effects vary from person to person because of the unique composition of each individual's microbiome.

Nonetheless, anyone with prediabetes or diabetes — or, who wants to avoid those health risks — should monitor how their blood sugar levels respond to beverages, syrups, and foods sweetened with sugar substitutes.

Instead of opting for "diet" beverages, stick with water, black coffee, and green or black tea.

And "treats" that are artificially sweetened are mostly made from highly processed, inflammatory carbs that create additional health woes — so stick with fresh fruits that don't spike your glucose level.