In a landmark 14-year study, researchers have found that artificially sweetened drinks raise the risk of developing type 2 diabetes by more than a third, significantly higher than those loaded with sugar. It challenges the long-standing perception of diet drinks being a healthier alternative and suggests they may carry metabolic risks of their own.
In the first longitudinal study of its kind, led by Monash University, researchers tracked 36,608 participants over an average period of 13.9 years to assess how both sugar-sweetened beverages (SSBs) and artificially sweetened beverages (ASBs) impacted health outcomes. The self-reported health data, from the Melbourne Collaborative Cohort Study, was drawn from participants aged 40 to 69 years at the time of recruitment.
The researchers categorized both ASB and SSB intake into distinct groups: never or less than once a month; one to three each month; one to six drinks a week; and more than one beverage a day. Then, the association of sweetened beverage intake with the incidence of type 2 diabetes was assessed using modified Poisson regression and adjusted for lifestyle, obesity, socioeconomic and other confounding factors.
What they found was that drinking just one can of artificially sweetened soda increased the risk of developing type 2 diabetes by 38%, compared to people who didn’t consume these drinks at all. For those consuming the same amount of sugary drinks, the risk was 23% higher.
“Artificial sweeteners are often recommended to people at risk of diabetes as a healthier alternative, but our results suggest they may pose their own health risks,” said senior author Barbora de Courten, a professor at Monash University and RMIT, which was also involved in the study.
After the researchers adjusted the sugar-sweetened drinks data to account for BMI and waist-to-hip ratio, the statistical association was lost, suggesting that obesity is a mediating factor in this cohort. Essentially, the SSB–diabetes link appears to be driven largely by weight gain.
The same could not be said for the artificial sweetener group, however.
When the ASB data was adjusted to factor in BMI, the risk went from an unadjusted 83% to 43%, and when it was again scaled to account for waist-to-hip ratio, it remained at 38%. This suggests there's more than obesity at play. The researchers believe this result is due to an independent metabolic effect, possibly gut microbiome disruption or a change in glucose metabolism.
While the study didn't identify which artificial sweeteners were at play, likely types include aspartame, saccharin and sucralose. Of these, some are poorly absorbed (sucralose), others are metabolized quickly (aspartame), and some are excreted in urine (acesulfame potassium, or ace-k), which may influence metabolic pathways differently.
There have been several recent studies looking into artificial sweeteners and diabetes, including a 2023 paper that linked the dietary additive with an elevated risk of type 2 diabetes mellitus (T2DM). While a 2024 meta-analysis found that, so far, the association is not well understood.
The researchers point to earlier studies that have shown some evidence of aspartame triggering postprandial insulin responses similar to sucrose (sugar), and saccharin and sucralose being linked to gut microbiome disruption and impaired glucose tolerance in as little as two weeks.
Evidence suggests that artificial sweeteners can alter the composition and function of gut bacteria, leading to glucose intolerance – a precursor to type 2 diabetes. And that some sweeteners may trigger insulin release, desensitize metabolic responses over time, or confuse the body’s glucose regulation system – even without actual sugar in the picture.
Another hypothesis is that regular exposure to the kind of intense sweetness that artificial products deliver may condition the body to anticipate sugar calories that never come, affecting appetite regulation, insulin sensitivity and broader metabolic pathways. However, the authors suggest that how sweeteners affect the gut microbiota and glucose regulation are the most likely drivers of increased diabetes risk.
The study is yet more evidence that argues artificial sweeteners may not be "safer" than refined sugar, when it comes to broader health risks – and as such, the researchers highlight, they should be under more scrutiny when it comes to public policy and dietary recommendations.
“We support measures like sugary drink taxes, but our study shows we also need to pay attention to artificially sweetened options," said de Courten. "These are often marketed as better for you; yet may carry their own risks. Future policies should take a broader approach to reducing intake of all non-nutritive beverages.”
The study was published in the journal Diabetes & Metabolism.
Source: Monash University
