For decades, dietary guidelines have painted sugar with a broad brush. But a sweeping new study suggests the story is more nuanced — and the real villain might not be sugar itself, but how we consume it.
In the largest and most detailed study of its kind, scientists at Brigham Young University and several German institutions have found a striking pattern: sugars consumed as liquids — like soda and even fruit juice — are consistently linked to a higher risk of type 2 diabetes. Meanwhile, sugars eaten in solid foods, including ordinary table sugar, may pose no such danger. In fact, they might even offer modest protection.
“This is the first study to draw clear dose-response relationships between different sugar sources and type 2 diabetes risk,” said Karen Della Corte, a nutritional science professor at BYU and lead author of the study, published in Advances in Nutrition. “It highlights why drinking your sugar — whether from soda or juice — is more problematic for health than eating it.”
When Sweetness Turns Sour
The researchers pooled data from 29 large cohort studies across Europe, North and South America, Asia, and Australia. In total, they examined the dietary habits of more than 800,000 people and tracked who went on to develop type 2 diabetes. By applying dose-response meta-analysis — a technique that teases out risk across a full range of intakes — they found a consistent trend.
Each additional 12-ounce serving of sugary beverages per day increased the relative risk of type 2 diabetes by 25%. And the danger started immediately — even one daily soda raised the odds. Fruit juice wasn’t much better: each 8-ounce serving bumped risk up by 5%.
The risks were “moderate certainty,” according to the study’s rigorous grading system. But unlike much prior research, the analysis adjusted for body weight, calorie intake, physical activity, smoking, and other key lifestyle factors, suggesting the effects were not just a reflection of an overall unhealthy diet.
“These associations persisted even after adjusting for body mass index and energy intake,” the authors wrote. That means the sugar itself, especially when drunk, seems to have a unique impact on the body.
A Sweet Surprise
If sugary drinks are a danger, what about sugars in other forms? Here’s where things get interesting.
When participants consumed 20 grams of total sugar a day — roughly five teaspoons — as part of solid foods, their risk of diabetes actually declined slightly (by about 4%). The same was true for sucrose, the kind of sugar found in many baked goods and added to cereal.
These inverse associations came as a surprise. “Our results do not support the common assumption that dietary sugar intake, irrespective of type and amount, is consistently associated with an increased risk of type 2 diabetes,” the authors wrote.
Instead, context appears to matter. When sugars are consumed as part of nutrient-dense foods — like fruit, yogurt, or whole grains — they don’t seem to overwhelm the liver or spike insulin in the same way that sugary drinks do. Fiber, fat, and protein in those foods may slow the absorption of sugar and blunt its metabolic effects.
“This suggests that the food source in which sugars are consumed needs to be considered,” Della Corte said.
Why Liquid Sugar May Be the Culprit
The difference likely lies in how the body metabolizes liquid sugars. Beverages like soda and juice are rapidly absorbed and deliver a concentrated blast of glucose and fructose to the liver. This can overload metabolic pathways, drive fat accumulation in the liver, and promote insulin resistance — all precursors to diabetes.
Controlled feeding trials support this idea. For example, studies have shown that consuming beverages sweetened with fructose increases liver fat and reduces insulin sensitivity, even when the total calorie intake stays the same.
One experiment cited by the researchers found that drinking the equivalent of two sugary sodas a day for 10 weeks increased fasting insulin and blood glucose levels — but only when the sugar was consumed as a drink. Similar doses of glucose did not have the same effects.
“Fructose-containing SSBs (sugar-sweetened beverages) uniquely disrupt liver metabolism and elevate insulin resistance,” the study concluded.
Even fruit juice, often marketed as a healthy choice, delivered no reprieve. Despite its vitamin content, fruit juice’s high sugar concentration and lack of fiber meant it behaved metabolically more like soda than whole fruit. “It’s a poor substitute for whole fruits,” the authors wrote.
Implications for Dietary Guidelines
For years, health organizations like the World Health Organization and the American Heart Association have called for limiting all added sugars. But the BYU-led team says those guidelines may need refining.
Rather than aiming blanket restrictions at all sugars, future recommendations could focus more precisely on liquid sugar. According to the study, there is no safe threshold for sugary drinks — the risk begins to rise from the first sip.
“Our findings suggest the importance of sugar type in determining the association of dietary sugar,” the authors wrote. “With higher liquid sugar intakes apparently linked to greater harm.”
This doesn’t mean added sugars in food get a free pass. But it does highlight the need for a more granular view — one that distinguishes between a soda and a bowl of oatmeal with a spoonful of brown sugar.
As Della Corte put it: “Rather than condemning all added sugars, future dietary guidelines might consider the differential effects of sugar based on its source and form.”
Not so fast…
This study is among the most comprehensive ever undertaken on the subject, including over half a million participants and adjusting for a broad range of confounders. The dose-response method allowed researchers to move beyond “high vs. low” comparisons and instead map risk across realistic ranges of consumption.
But there are limitations. The evidence for fructose and added sugar in isolation was weak and inconsistent, partly due to differences in how studies defined and measured these sugars. The researchers also could not include specific foods like ice cream or candy, focusing instead on broader categories and beverages.
Importantly, the authors stop short of saying sugar in solid food is good for you. Rather, they argue that when consumed in the context of a balanced diet, and not as part of sugary drinks, solid-form sugar doesn’t show a consistent harmful association with diabetes risk.
Their wording is careful:
“Our results do not support the common assumption that dietary sugar (i.e., total sugar and sucrose), irrespective of type and amount, is consistently associated with increased T2D risk.”
They also note that the certainty of evidence for these associations is moderate or low, and call for more research to untangle the effects of sugar in different contexts.
Still, the message is clear. If you’re worried about diabetes, the form your sugar takes may be just as important as how much you consume.
The next time you’re choosing between apple juice and an apple, science may have tipped the balance.
