Does Diet Soda Affect Blood Sugar Levels?

How Artificial Sweeteners in Diet Soda Can Affect Your Health

Artificial sweeteners were developed over a century ago as a food additive to provide sweetness without the caloric content of sugar. A zero-calorie, guilt-free option - or so they say. The United States Food and Drug Administration (FDA) has approved five artificial sweeteners:¹

1. Aspartame
2. Saccharin
3. Acesulfame potassium
4. Neotame
5. Sucralose

Aspartame is a white, odorless powder found in many processed foods. It is 200 times sweeter than regular sugar with many studies showing that aspartame has been linked to the exacerbation of diabetes, obesity, headache, seizures, depression, and arthritis, to name a few.² While aspartame does not directly raise or lower blood sugar and insulin (no glycemic effects), studies show it can be harmful.

Tip from an MD: Be sure to check the ingredients list on the back of food labels. In the United States, it is required by law to list if aspartame is added. If so, place it back on the shelf!

Saccharin is 300 - 500 times more potent than sugar and passes through the GI system undigested. This led one research study to show that saccharin can actually alter our natural gut flora (healthy bacteria in the gastrointestinal tract).³ While some studies show that it does lower insulin levels and improves blood sugar control, these were only in mice models. In humans, saccharin consumption has been linked to the increased accumulation of body fat, despite diet and exercise. 

Tip from an MD: Saccharin tends to be in food and drinks labeled diet, sugar-free, or light. Fountain Diet Coca-Cola contains a mixture of aspartame and saccharin, while store bought Diet Coke uses aspartame exclusively. Many states have filed class action suits against Coca-Cola for not stating this.⁴

Acesulfame potassium was approved in 2003, is 200 times sweeter than sucrose, and bears no glycemic effects. It also passes through the body unmetabolized and is excreted by the kidneys.⁵

Neotame was approved in 2002 for large scale food manufacturing and is not available commercially. Remarkably, this chemical is 7,000 times sweeter than sucrose!⁶

Sucralose is a more natural derivative of sucrose. In human studies, sucralose overall showed no statistically significant differences between the study and control groups when measuring participants fasting plasma glucose and A1c.⁷

Tip from an MD: Splenda is a common sweetener that uses sucralose. It can be added to diet sodas, chewing gum, and desserts.

<p class="pro-tip"><strong>Learn about </strong> <a href="/blog/sugar-substitutes-and-artificial-sweeteners-part-3">using artificial sweeteners responsibly</a>.</p>

How Diet Soda Affects Insulin

Studies show that drinking diet soda alone does not directly cause diabetes,⁸ nor does it directly raise insulin levels.⁹ When combined with other food or glucose, however, those who consume diet soda have higher levels of insulin and what is called glucagon-like peptide 1 (GLP-1).¹⁰ This is important for several reasons.

GLP-1 is a hormone that helps to increase levels of insulin. Many medications used to treat diabetics are GLP-1 agonists, for those with insulin resistance. Diet soda increases levels of GLP-1.¹¹ More studies will need to be done to determine the clinical significance of this, and what the health ramifications are, but suffice it to say that diet soda does directly impact our digestive hormones, and should be avoided in the setting of diabetes. 

How Diet Soda Can Affect Blood Pressure

Studies show that diet soda and other sweetened beverages contribute to gaining weight, metabolic syndrome, and diabetes. These health concerns then contribute to high blood pressure (hypertension).¹² If someone suffers from high blood pressure, they should avoid diet soda.

Tip from an MD: Do not stop caffeinated diet sodas cold turkey. This can result in rebound caffeine withdrawal headaches. Taper diet soda out of your diet slowly, especially if you consume multiple sodas a day. Switch this with a carbonated beverage for a sugar-free bubbly water like La Croix.

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Risks of Drinking Diet Soda

1. Diet drinks encourage your sweet tooth. 
2. Fatty liver disease. Consuming sugar-sweetened beverages increases our risk of fatty liver disease, which includes things like cirrhosis, steatohepatitis, and hepatic steatosis.¹³ While diet soda itself does not directly causes liver disease, mixing sodas with alcohol only adds to the problem. 
3. Increased Appetite. When consuming diet soda and other artificial sweeteners, the body believes it is consuming calories. The gut releases digestive enzymes to receive these calories and the mouth salivates, all of which increase our appetite. For those who struggle with cravings and eating disorders, artificial sweeteners can make avoiding these behaviors worse. Artificial sweeteners are also much more potent than regular sugar, which alters our natural perception of taste.
4. Diabetes. Studies show that diet soda can raise A1c levels and significantly increases someone’s risk of developing metabolic syndrome, which includes levels of bad cholesterol (LDL).
5. More belly fat: one study found a 41% increase in risk of being overweight for each daily can or bottle of diet soda.¹⁴
6. Stroke¹⁵ and heart disease.¹⁶ Studies show that the risk of stroke is significantly higher for both men and women who consumed at least one soda a day. Studies also show soda can negatively impact lipid levels, inflammatory markers, and leptin, which is a hormone that controls appetite and feeling full. 
7. Gut bacteria imbalances. Artificial sweeteners, like aspartame, can inhibit some of the natural enzymes within the gut.¹⁷ This changes how our metabolism processes other food, which in turn impact the concentration of healthy bacteria in the gut. 
8. End stage kidney (renal) disease. One population study showed that those who consumed more than 7 diet sodas a week were 1.83 times more likely to develop kidney disease in the setting of obesity.¹⁸

Diet Soft Drinks Are Linked to Depression, Especially in Women

Depression is one of the most common mental illnesses in the world, with more than 264 million suffering internationally. Nutritional psychiatry is a new field that is emerging to better identify how intricately diet improves or worsens mental health.

In one population study, researchers screened 820 subjects, with 29.2% meeting criteria for a major depressive (MD) episode. After accounting for all confounds, poor diet quality was linked with depression. Those with major depression consumed regular amounts of soda and artificial juice, creating the argument that perhaps diet soda can worsen depression.¹⁹

Another study found that the odds of depression increased by 5% for every sugary drink consumed. Women and non-hispanic Black people tended to be 60% more likely to suffer depression when consuming diet soda, and those who were unemployed with having only a high school level education or less had greater associations.²⁰

Adolescents that consume soda are 1.27 times more likely to exhibit depressive symptoms than those who do not consume soda.²¹ 

Tip from an MD: If you struggle with depression, in addition to seeking counseling and treatment, do a major overhaul of your diet. In just 1 week, you’ll be surprised how quickly some of your symptoms alleviate!

<p class="pro-tip"><strong>Learn which </strong> <a href="/blog/foods-for-mental-health">foods can support mental health</a>.</p>

Should You Avoid Diet Soda?

Albeit approved by the FDA, artificial sweeteners should be avoided, as their consumption on a large scale is linked to higher rates of obesity, weight gain, and type 2 diabetes, among a host of other health problems. Some artificial sweeteners can be thousands of times more potent than regular sugar, which only adds to sugar cravings and eating disorders. Sure, swapping artificially sweetened drinks in for sodas will reduce your sugar intake, but it may set you up for a list of other health risks. 

Should Diabetics Avoid Diet Soda?

Diet soda is not ok for diabetics. While diet soda does not directly cause diabetes, one study found that those who drank one or more servings a day had a risk of developing type 2 diabetes 67% greater than those who do not drink diet soda.²² Other studies have clearly demonstrated the increased risk of high blood pressure, metabolic syndrome, and kidney disease, which are already sore points for diabetics. 

Healthier Alternatives to Diet Soda

• Carbonated water with a splash of fruit juice (not from concentrate), lime, or lemon. 
• Unsweetened tea.
• Coffee, but be sure to watch your caffeine intake, as caffeine can be dehydrating.
• Stevia leaves. This plant originates from Paraguay in South America, and has been used by natives for centuries as a natural sweetener. It provides a low calorie sweetening affect (2.7 kcal/g) and is 450 times sweeter than sucrose. Stevia has antioxidant properties, neutralizes free radicals, and contains polyphenols that can prevent heart disease, atherosclerosis, and cancer.²³

Tip from an MD: Consider purchasing a Soda Stream, as this reduces generating plastic waste from cans and bottles. I sometimes add cut up strawberries or cucumber to my carbonated water. 

Is a CGM Helpful for Diet Soda Drinkers? 

A continuous glucose monitor will show minimal changes to your blood sugar after consuming a diet soda, because diet soft drinks do not directly increase blood sugar. A CGM does not directly measure insulin, GLP-1, or the metabolic changes taking place inside the gut. If you’re drinking a diet soda with a meal, snack, or alcohol, then a CGM will show how your body responds in a matter of minutes, as diet soda disrupts natural digestive hormones. 

<p class="pro-tip"><strong>Learn more about </strong> <a href="/blog/what-is-a-continuous-glucose-monitor">how CGMs work</a>.</p>

Final Thoughts on Diet Soda

If you struggle with glycemic control, obesity, high blood pressure, or kidney disease, diet soda and artificial sweeteners should be avoided. They have been clinically proven to exacerbate these chronic illnesses, and increase your risk of depression, stroke, liver disease, and metabolic syndrome. Be sure to read the labels on the back of food and drinks, and replace them with alternatives that use natural sweeteners like Stevia.