Why just one can of diet soda may be worse for your health than regular soda

A NEW Australian study has found that drinking just one can of diet soda a day may increase the risk of developing type 2 diabetes by 38%.

Surprisingly, the study suggests that artificially sweetened drinks may pose an even greater risk than regular sugary beverages, which were linked to a 23% higher risk. Researchers from Monash University, RMIT University, and the Cancer Council Victoria tracked more than 36,000 Australian adults over nearly 14 years. 

The study was led by Distinguished Professor Barbora de Courten, Associate Professor Allison Hodge, and PhD student Robel Hussen Kabthymer.

What did the researchers find?

Published in the journal Diabetes & Metabolism, the findings raise concerns about the health effects of both sugar-sweetened and diet drinks.

"Drinking one or more of these beverages each day, whether sweetened with sugar or artificial substitutes, was linked to a significantly higher chance of developing type 2 diabetes," said Hussen Kabthymer.

Professor de Courten, the senior author, added: "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."

Why are artificial sweeteners a concern?

While the link between sugary drinks and diabetes can largely be explained by obesity, the connection between artificially sweetened drinks and type 2 diabetes remained strong even after adjusting for body weight. This suggests a potentially direct effect on metabolism.

What are the public health implications?

Professor de Courten said the findings could influence public health policy.

"We support measures like sugary drink taxes, but our study shows we also need to pay attention to artificially sweetened options. 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 analysed data from the long-running Melbourne Collaborative Cohort Study, also known as Health 2020, which involved participants aged 40–69 and accounted for diet, exercise, education, and health history.

Type 2 diabetes affects around 1.3 million Australians and over 500 million people worldwide, with the majority of cases linked to diet and lifestyle.