Does Pepsi Zero Increase Insulin Release?
No, Pepsi Zero (containing non-nutritive sweeteners like aspartame and acesulfame-K) does not increase insulin secretion in most people, though the evidence shows some nuanced effects on gut hormones that don't translate to clinically significant insulin changes.
Direct Evidence on Insulin Response
The most definitive evidence comes from a 2018 randomized controlled trial that directly tested this question. When healthy adults consumed carbonated beverages with aspartame and acesulfame-K (the sweeteners in Pepsi Zero) daily for 12 weeks, there was no significant effect on insulin sensitivity or insulin secretion 1. This study specifically measured the Matsuda Insulin Sensitivity Index and multiple insulin secretion indexes, finding no differences compared to unsweetened carbonated water.
Similarly, a 2020 study found that daily consumption of pure aspartame or sucralose for 2 weeks had no effect on glucose metabolism or insulin sensitivity in healthy adults 2.
The Gut Hormone Nuance
There is an interesting physiological finding that doesn't translate to clinical concern: diet soda can increase GLP-1 (glucagon-like peptide 1) secretion by 34-43% in healthy individuals and those with type 1 diabetes, but NOT in people with type 2 diabetes 3. However, this GLP-1 increase occurred without any changes in glucose or C-peptide (insulin) levels 3. This means the gut hormone response exists but doesn't trigger actual insulin release.
The American Academy of Pediatrics guideline confirms this, noting that in youth with diabetes, "there were no differences in glucose or C-peptide secretion in people with either type 1 or type 2 diabetes mellitus after NNS consumption" 4.
Important Caveats
The Sucralose Exception
One 2013 study found that sucralose specifically (not aspartame/acesulfame-K) caused a 20% greater insulin response in obese individuals who never normally consumed non-nutritive sweeteners 5. This suggests:
- Context matters: If you're obese and don't regularly consume artificial sweeteners, there may be an acute adaptation period
- Regular consumers are different: The 12-week study showing no effect 1 suggests tolerance develops with regular use
- Sweetener type matters: Sucralose may behave differently than aspartame/acesulfame-K
Long-term Metabolic Concerns
While acute insulin release isn't increased, the 2004 Diabetes Care guidelines note that "non-nutritive sweeteners are safe when consumed within acceptable daily intake levels" but don't address long-term metabolic effects 6. The 2019 AAP guideline acknowledges associations between diet soda and diabetes risk in observational studies, but these associations disappeared after adjusting for baseline obesity, suggesting reverse causation (people at risk for diabetes choose diet soda, not that diet soda causes diabetes) 4.
Clinical Bottom Line
For regular consumers of Pepsi Zero, there is no clinically significant insulin release. The beverage is metabolically inert regarding acute insulin secretion. However, if you're obese and have never consumed artificial sweeteners before, there may be a transient adaptation period where some insulin response occurs, particularly with sucralose-containing products.
The FDA-approved sweeteners in Pepsi Zero (aspartame and acesulfame-K) have been "shown to be safe when consumed by the public, including people with diabetes" 6.