What Happens to Your Blood Sugar When You Drink Diet Coke Regularly

Diet Coke does not contain sugar and has little direct impact on blood sugar levels. However, drinking it too often can carry potential health risks.

Diet sodas contain aspartame and other artificial sweeteners. These sweeteners are virtually free of calories and carbs, so they don’t cause the same blood sugar spikes as regular soda. However, research on the use of artificial sweeteners to manage blood sugar levels is mixed.

Many studies show that sweeteners like aspartame and sucralose do not cause major changes in blood sugar or insulin levels. But other research suggests that these sweeteners could still affect how your body processes glucose or responds to insulin over time.

A 2020 study of people with type 2 diabetes found higher insulin resistance in people who regularly consumed artificial sweeteners than in those who did not. Insulin resistance occurs when your body’s cells don’t respond properly to insulin. This makes it more difficult to keep blood sugar levels within a healthy range.

Evidence on the long-term health effects of artificial sweeteners in diet soda remains limited. Some research suggests potential links to certain health risks, such as:

• Degraded mental health: Artificial sweeteners have been linked to irritable mood and an increased risk of mental health problems like depression.
• Faster cognitive decline: Over time, regular consumption of artificial sweeteners can affect your cognition. A large 2025 study linked long-term use of artificial sweeteners like aspartame to an increased rate of cognitive decline.
• Higher risk of heart disease: Some studies suggest that high consumption of artificial sweeteners may increase the risk of heart disease.
• Weight gain: Some research has linked artificial sweeteners to weight gain, while others have found no association.
• Increased risk of cancer: The World Health Organization’s International Agency for Research on Cancer (IARC) has classified aspartame as “potentially carcinogenic to humans” (Group 2B). However, the United States Food and Drug Administration (FDA) states that current evidence does not support a link between aspartame and cancer in humans.
• Complications of diabetes: Worsening diabetic eye disease (retinopathy) and higher A1C levels have been observed in some people who regularly consume artificial sweeteners.

The FDA considers the artificial sweeteners typically found in Diet Coke to be safe for most people when used in moderation.

For context, a 130-pound person would need more than 75 packets of Equal® or 23 packets of Splenda® in a day to exceed the current recommended limits.

Indirect effects

Beyond blood sugar, diet soda can also affect gut health. Some studies suggest that artificial sweeteners can alter the balance of gut bacteria. This can influence how your body handles sugar. It can also trigger cravings for real sugar, even if it doesn’t contain any.

One study found that cutting back on artificial sweeteners reduced sugar cravings in just one week.

Artificial sweeteners in diet soda are considered safe by the FDA when consumed within recommended limits. If you’re concerned about potential health effects, consume diet soda occasionally as part of a balanced diet. When possible, opt for water, sparkling water or unsweetened tea instead.