According to a new study by Harvard University, every extra cup of coffee you drink reduces the risk of diabetes by 10%, but the benefits are greatly reduced by adding sugar
Type 2 diabetes (T2D) is a common chronic disease that affects more than 540 million people worldwide.
With the change of living and eating habits, diabetes has become the third biggest factor affecting human health.
In China, there are more than 114 million adults with diabetes, accounting for a quarter of the world’s diabetes patients, the highest number in the world, and this number continues to rise.
Coffee, a life-saving artifact of the modern age, is one of the most popular beverages in the world.
Because it contains a large amount of caffeine, it is often drunk by people to wake up and improve work efficiency.
Past research has shown that regular coffee consumption can provide multiple health benefits.
Multiple studies have shown that regular coffee consumption associated with a lower risk of type 2 diabetes, however, its unclear whether adding sugar, artificial sweeteners, cream, etc. to coffee changes the benefits of coffee in reducing diabetes risk.
On January 18, 2025, Bingchang Hu of the Harvard T.H. Chan School of Public Health published a paper in the American Journal of Clinical Nutrition entitled “Coffee Consumption, Additive Use, and Risk of Type 2 Diabetes-Results from Three Large Prospective US Cohort Studies “.
An additional cup of coffee per day (without any additives) associated with a 10 percent lower risk of type 2 diabetes, and the addition of sugar and artificial sweeteners to coffee reduced this association, suggesting that sugar and artificial sweeteners may offset coffee’s diabetes benefits.
For the study, the researchers analyzed data from three large prospective cohort studies in the United States, including the Nurses’ Health Study (NHS), NHS II, and the Health Professionals Follow-up Study (HPFS), which included a total of 150,000 participants who obtained information on coffee and coffee additive intake through dietary information.
Including sugar, artificial sweeteners, cream, and non-dairy coffee brighteners, we analyzed whether coffee additives alter the benefits of coffee in reducing diabetes risk.
Overall, the average coffee intake was 2.6 cups per day in NHS, 1.7 cups in NHS II, and 2.1 cups in HPFS, with each cup measuring 8 ounces (about 240 ml).
About 32-42 percent of participants regularly added sugar to their coffee, about 10 percent added artificial sweeteners, less than 10 percent added non-dairy coffee whiteners, and 6 percent added cream.
The pooled analysis found that for each additional cup of coffee (about 240 ml) consumed without any coffee additives, the risk of diabetes reduced by 10%.
The association weakened in the case of added sugar (an average of 1 teaspoon per cup, about 5 grams), with each additional cup of coffee consumed associated with a 5 percent lower risk of diabetes;
The association also weakened when artificial sweeteners added, with a 7 percent reduction in diabetes risk for each additional cup of coffee consumed.
Adding cream did not change the relationship between coffee intake and diabetes risk, and there no association between coffee intake and diabetes risk when non-dairy coffee brighteners added.
Adding both sugar and artificial sweeteners not associated with a reduced risk of diabetes.
Artificial sweeteners and non-dairy coffee brighteners significantly reduced the benefits of coffee on diabetes when coffee consumption exceeded 3 cups per day.
According to the researchers, several bioactive compounds in coffee have shown to inhibit pro-inflammatory pathways associated with diabetes pathogenesis, including chlorogenic acid, trigonelline, caffeine, and phenolic compounds.
Added sugars and artificial sweeteners, which can lead to weight gain, pro-inflammation, and increased risk of diabetes, could explain the underlying mechanisms that offset coffee’s benefits.
It is worth mentioning that adding sugar and artificial sweeteners to coffee will also offset the benefits of coffee on the liver.
On January 10, 2025, researchers from The School of Public Health of Guangzhou Medical University published a paper in The Journal of Nutrition entitled “Association of Sugar sweetened, Artificially Sweetened, and Unsweetened Coffee Consumption with Chronic Liver Disease and Liver Related Events: A Large Prospective Cohort Study “research paper.
Studies have shown that moderate consumption of unsweetened, artificial sweetener coffee significantly reduces the risk of chronic liver disease and liver-related events, while adding sugar and artificial sweeteners to coffee increases the risk of chronic liver disease and liver-related events.
This large prospective study showed that drinking an additional cup of coffee per day (without any additives) associated with a 10% lower risk of type 2 diabetes, while sweetened, artificially sweetened coffee weakened coffee’s protective effect against diabetes.
In addition, coffee without any additives also helps protect the liver, while added sugar, artificial sweeteners can offset this benefit.
References:
- https://doi.org/10.1016/j.ajcnut.2025.01.017
- https://doi.org/10.1016/j.tjnut.2025.01.009
