Does Diet Soda Affect Insulin?

Avoiding sugary beverages is an important part of maintaining healthy blood sugar levels for people with diabetes and those who are at risk for it. While some forego drinking soda altogether, others opt for diet sodas, which get their flavor from artificial sweeteners such as aspartame, saccharin and sucralose.

Artificially sweetened diet sodas typically have no calories, so they were once believed to have no effect on blood glucose or insulin levels. But mounting evidence suggests that while consuming artificially sweetened beverages doesn't raise blood sugar in the short term, it can negatively affect the body in other unexpected ways, including increasing the risk of type 2 diabetes.

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Drinking diet soda has long been recommended as a strategy for reducing calorie intake while still enjoying sweet-tasting beverages. Because artificial sweeteners have few to zero calories, they don't raise blood sugar, as confirmed by a March 2018 meta-analysis in the ​European Journal of Clinical Nutrition​. However, artificial sweeteners may change how the body absorbs real sugar in the long run.

According to a September 2013 study in ​Diabetes Care​, artificial sweeteners have been linked to insulin resistance, a condition caused by chronic high blood sugars. Insulin resistance increases a person's risk of type 2 diabetes. Though more research is needed, evidence indicates that artificial sweeteners increase insulin resistance by disrupting the gut microbiome.

The gut microbiome — the unique collection of bacteria, viruses and fungi that naturally live in the digestive tract — is a critical and delicate system that is just beginning to be understood. But it is believed to play an important role in obesity and impaired insulin function, according to a May 2016 evidence review in the ​Postgraduate Medical Journal​.

According to an article in the September 2018 issue of ​Current Diabetes Reports​, studies have shown that people with type 2 diabetes have an altered gut microbiome compared to those with normal insulin function. Though it is not yet clear exactly how the gut microbiome affects insulin resistance, the early evidence suggests it's time to rethink diet soda's place in a low-sugar diet.

Osama Hamdy, MD, PhD, director of the inpatient diabetes program at Harvard's Joslin Diabetes Center, thinks the negative association between diet soda and metabolic health is important to consider when making healthy diet choices. "Although it's just an association — which means it is not the ​cause —​ I personally don't recommend [drinking diet sodas], as they change intestinal microbiota," he says. "[But] if you ask me to choose between sugar-sweetened beverages and diet sodas, I will choose diet sodas."

Exactly how artificial sweeteners affect the gut microbiome and long-term blood sugar levels remains to be seen. Much more research is needed, as many of the studies to date have been conducted on either rodents or people without diabetes.

​Read more:​ What You Need to Know About the Effects of Stevia on Insulin

Diet sodas haven't only been linked to metabolic disorders. According to a number of studies, including a meta-analysis in the July 2017 ​Canadian Medical Association Journal​, artificial sweeteners have been linked to an increased risk of weight gain, heart disease and stroke.

Artificial sweeteners and low-calorie sweeteners (such as stevia) can also change people's perception of the natural taste of food. Because they're significantly sweeter than regular sugar, people who consume a lot of these sweeteners may find that foods containing natural sugars taste less sweet — and ultimately less palatable. Research shows that this could ultimately create a dislike for healthy foods, including filling, fiber- and nutrient-rich fruits and vegetables, according to Harvard Health Publishing.

If naturally sweet foods lose their appeal, it's more likely a person will turn to unhealthier options like candies and desserts to satisfy their sugar cravings. Over time, these food choices can lead to weight gain, which diabetes statistics show is a risk factor for developing the condition.

Though there are signs that artificially sweetened beverages may have a negative effect on your health, the results are not yet conclusive. While some studies show that diet soda may disrupt your metabolic system, others have found that diet soda does ​not​ lead to increased insulin resistance, according to a study in the December 2016 ​Journal of Nutrition​.

Contradictory results at this stage aren't too surprising: It's challenging to study the effects of artificial sweeteners because there are many different types and they're in many of the foods we eat on a daily basis — not just diet sodas. Therefore, it will be some time before the health effects of diet soda are fully understood.

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In the meantime, the American Diabetes Association affirms that consuming artificial sweeteners in limited amounts ​can​ be an effective way to reduce your overall sugar and calorie intake. So while it is a good idea to limit your consumption of diet sodas, you might not have to cut them out completely.

Discuss diet soda and artificial sweeteners with your doctor or dietitian, and ask them to help you create a plan to manage your blood sugars and metabolic health.