Several studies have investigated the effects of stevia on blood sugar levels.
A 2016 study reported that dried stevia leaf powder significantly lowered blood sugar levels in people with diabetes, both while fasting and after eating. The participants in the study also saw a reduction in their triglyceride and cholesterol levels.
The researchers concluded that stevia is safe for people with diabetes to use as a substitute for sugar and other sweeteners.
A 2013 study in rats reported that using whole stevia leaf powder as a dietary supplement led to lower blood sugar levels. The results also suggested that stevia could reduce liver and kidney damage in the animals.
Other research from 2015 found that nonnutritive sweeteners such as stevia had antioxidant potential and significantly lowered blood sugar levels in mice.
Stevia may also reduce hunger and improve satiety in people.
In a small-scale study, researchers gave participants a snack to eat before their main meal, which is a dieting technique known as preloading. The preload snack contained either stevia, aspartame, or sucrose, also known as table sugar.
The sucrose preload had 493 calories, while both the stevia and aspartame preloads only contained 290 calories. Despite this, all three groups of participants reported similar hunger and satiety levels.
The people who ate the stevia preloads had significantly lower blood glucose levels after meals when the researchers compared them with the sucrose group. They also had lower insulin levels than those in both the aspartame and sucrose groups.
However, a more recent review of 372 studies suggested that evidence for harmful or beneficial effects is inconclusive.
It is also important to note that most of the research uses dried stevia leaf rather than stevia extracts.
Stevia extracts typically contain other ingredients, some of which may affect blood sugar levels. However, stevia leaf does not have GRAS status with the FDA, who do not allow manufacturers to use it as a sweetener.