Artificial sweeteners are widely used as low-calorie or non-caloric sugar substitutes. Fasting blood work is a common medical procedure designed to measure baseline levels of various substances in the blood. Fasting ensures that recent food or drink intake does not influence results, as consumption can temporarily alter levels of nutrients, sugars, and fats. A frequent question arises regarding whether artificial sweeteners might interfere with the accuracy of these essential fasting blood tests.
Common Artificial Sweeteners
Artificial sweeteners are synthetic compounds that provide sweetness similar to sugar but with significantly fewer or no calories. They are hundreds to thousands of times sweeter than sucrose, meaning only small amounts are needed. The U.S. Food and Drug Administration (FDA) has approved several for use, commonly found in diet beverages and “sugar-free” foods.
Common examples include:
Sucralose (Splenda)
Aspartame (Equal, NutraSweet)
Saccharin (Sweet ‘N Low)
Acesulfame potassium (Ace-K or Sunett)
Purified stevia leaf extracts (Truvia, PureVia) and monk fruit extract (Luo Han Guo)
These sweeteners are used to reduce sugar intake while maintaining palatability.
Direct Effects on Fasting Glucose and Insulin
Artificial sweeteners are designed to provide sweetness without significant calories or carbohydrates, and typically do not acutely raise blood glucose levels in a fasting state. For most individuals, consuming these sweeteners during a fasting period does not directly impact fasting glucose or insulin readings because they are not metabolized like natural sugars. Many studies indicate sucralose, for instance, has little to no effect on blood sugar and insulin levels.
Some research suggests certain artificial sweeteners might lead to an increase in fasting insulin levels, even if blood glucose remains stable. This effect may occur through sweet taste receptor stimulation. While long-term implications on gut microbiome and metabolic effects are ongoing research areas, they are not considered relevant for the immediate accuracy of acute fasting blood work. For a single fasting blood test, the direct, acute impact on glucose and insulin from consuming artificial sweeteners is often minimal or absent for most individuals.
Influence on Other Fasting Blood Markers
Beyond glucose and insulin, artificial sweeteners generally do not have a direct, acute impact on other common fasting blood markers, such as those in a lipid panel or tests for liver and kidney function. A comprehensive review found that artificial and stevia-based sweeteners did not significantly affect triglyceride, total cholesterol, LDL, or HDL levels. This suggests consuming these sweeteners during a fasting period for a lipid panel is unlikely to skew results.
Regarding liver function, some studies suggest long-term consumption might be associated with changes in liver enzymes or contribute to non-alcoholic fatty liver disease. However, for an acute fasting blood test, there is no immediate, direct effect on liver enzyme markers. Similarly, while some long-term observational studies explored associations with kidney function decline, newer research does not consistently support a causal relationship. Therefore, acute consumption of artificial sweeteners during fasting is not expected to alter kidney function test results like creatinine or urea.
Preparing for Fasting Blood Work
When preparing for fasting blood tests, strictly follow your healthcare provider’s instructions. Fasting typically means refraining from all food and drink, except plain water, for a specified period, often 8 to 12 hours. Plain water is allowed and recommended for hydration, as it does not interfere with test results.
While artificial sweeteners may not acutely impact all blood markers, it is safest to avoid them during the fasting window for the most accurate results. Diet sodas, for instance, may contain other ingredients that could affect blood sugar or other parameters. Chewing gum, smoking, or exercising should also be avoided, as these activities can affect digestion and metabolism. Always consult your doctor or the laboratory for specific instructions, as requirements vary depending on the tests.