What You Need to Know About the Effects of Stevia on Insulin

Stevia is a plant native to South America that has been used as a sweetener for hundreds of years, according to a May 2015 article in ​Nutrition Today​. But its natural sweetness is making it increasingly popular as a sugar substitute, according to stevia manufacturer Truvia, because it's calorie-free.

Yes, calorie-free. Stevia gets its sugar-like flavor from glycosides, sweet-tasting compounds the body can't metabolize and therefore don't deliver any energy, or calories.

Ounce for ounce, refined stevia is also 200 to 400 times sweeter than sugar, according to the FDA, yet it doesn't increase blood sugar levels. This makes it especially useful for people with diabetes. But the stevia plant's benefits might extend beyond its sweet taste: Limited research indicates that stevia may also increase the production and improve the action of the hormone insulin, which helps the body use and store glucose.

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Stevia is derived from ​Stevia rebaudiana​, a small, shrub-like plant that grows in Paraguay and Brazil. The glycoside compounds that provide stevia's characteristic sweetness — stevioside and rebaudioside — are derived from the plant's leaves, explains the May 2015 ​Nutrition Today​ article. There are two types of stevia: high-purity stevia leaf extract and unrefined stevia.

High-purity stevia extract is the only type that has been approved by the FDA for use as a food sweetener; it's made by extracting the sweet-tasting compounds from the stevia leaf. The FDA has also approved unrefined stevia — namely, whole leaves, dried leaves and stevia powders — to be sold as dietary supplements, but they haven't been approved for use as sugar substitutes due to the lack of available safety information.

When you eat, your body converts carbohydrates into sugar, or glucose, explains Harvard School of Public Health. High blood sugar — aka hyperglycemia — happens when there is too much glucose in the blood. The hormone insulin helps move glucose from your bloodstream and into the cells, which use it for fuel. If there is too much glucose in the blood on a regular basis, you can develop insulin resistance. This means your body is no longer able to use insulin effectively, leading to chronic hyperglycemia. Over time, insulin resistance can lead to type 2 diabetes.

Stevia is being increasingly studied as a tool to help manage and possibly prevent type 2 diabetes. Several small studies, including a study published in July 2018 by the American Diabetes Association (ADA), have found that stevia did not raise blood sugar or insulin levels in people with and without obesity. This is particularly important because obesity is a risk factor for developing type 2 diabetes.

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Stevia's blood sugar-friendly and calorie-free properties make it ideal for people who are concerned about their blood sugar levels and calorie intake. But it may have additional benefits as well, including promoting better insulin function, according to an October 2019 study in the ​Journal of Functional Foods​. Research shows that stevia may positively affect how glucose gets into the cells and may even increase insulin secretion.

According to a June 2012 study in the ​Journal of Nutrition​, stevia may also help you feel more full, meaning that you're less likely to overeat. The research into stevia's link with lowering blood glucose levels is still very new; only a few human trials have been conducted to date. More research is needed to fully understand how stevia affects insulin function and blood sugar levels.

Research on using stevia as a sweetener is still in its early stages, but the outlook seems promising. "The research specifically looking at pure stevia looks pretty good in terms of its efficacy and safety," says Heidi Karner, a registered dietitian nutritionist at Harvard's Joslin Diabetes Center.

But Karner points out that pure stevia — also known as rebaudioside A, or Reb-A — is typically unavailable at your local grocery store. "[Usually] you see [brands] like Truvia or Stevia in the Raw," she notes. "Those are actually combinations of Reb-A with other fillers. For instance, Truvia is Reb-A plus erythritol, which is a sugar alcohol. Stevia in the Raw is a combination of Reb-A and dextrose." It should be noted that sugar alcohols, including eythritol, can cause stomach upset or diarrhea when consumed too frequently, as described in a July 2015 review published in ​European Food Research & Technology​.

Pure stevia can help people lower their sugar intake, but non-sugar sweetener combinations that include stevia could cause unexpected health effects. An April 2015 study published in ​Gut Microbes​ found that non-sugar sweeteners may disrupt the health of the gut microbiome, the unique variety of bacteria, viruses and fungi that live in your digestive tract. The gut microbiome is believed to play a key role in obesity and possibly even insulin sensitivity.

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Non-sugar sweeteners like stevia also taste much sweeter than regular sugar, and research has shown that regularly consuming non-sugar sweeteners can change how you taste other foods. It might cause naturally sweet foods such as fruit to taste less sweet by comparison, according to a June 2015 study in ​Physiology & Behavior​.

If you're looking to add stevia to your diet, Karner recommends buying the purest form of stevia you can find, either online or in a health food store. And always make sure that you read the ingredients list. "It's important to be aware of what sugar substitutes contain," she says. "Some of the more popular [stevia] products are combinations of stevia and something else. Some of them are even combinations of stevia and artificial sweeteners like aspartame. That can be misleading."

Like other non-sugar sweeteners, stevia can help reduce sugar and calorie intake when used appropriately, according to statement by the ADA and the American Heart Association. However, the statement does not recommend using stevia to improve insulin sensitivity. If you are one of the 34 million American adults who have diabetes or are interested in adding stevia to your diet, ask your doctor or a dietitian to help you develop a plan that suits your individual needs.