Ultra-Processed Calories Linked to Worse Daily Blood Sugar in Type 2 Diabetes

The work is an observational study in people, published in 2026 in Diabetes Research and Clinical Practice. It included 190 adults with type 2 diabetes. Observational means the researchers looked at what people ate and how their glucose behaved. They did not assign anyone a diet. So the findings show an association, not a cause.

Each participant completed two 24-hour dietary recalls, in which they reported everything eaten in a day. They also wore a blinded continuous glucose monitor for 14 days. Blinded means the wearer could not see the readings, so the data should not have changed their behavior. The researchers sorted foods with the NOVA system, which groups foods by how much industrial processing they undergo.

The team then measured ultra-processed intake in two ways. The individual-level measure asked what share of a person's total energy, or total weight of food, came from ultra-processed items. The food-level measure looked at the foods themselves: the average ultra-processed share of energy across every food item a person reported, with each item counted.

The food-level measure was the one that tracked with glucose. After adjusting for demographic, lifestyle and clinical factors, a higher average ultra-processed energy share was linked to lower odds of spending more than 70% of the time in range. That figure is called time in range. The odds ratio was 0.59, with a 95% confidence interval of 0.38 to 0.92.

It was also linked to higher odds of spending at least 25% of the time above range. The odds ratio was 1.62 (95% CI 1.06 to 2.47). And it was linked to higher odds of a glucose management indicator of 7% or more. That indicator is an estimate of average glucose taken from monitor data. The odds ratio was 1.56 (95% CI 1.03 to 2.35).

The individual-level measure, the share of a person's whole day's intake, was not significantly associated with any of the monitor-based outcomes. The authors conclude that food-level measures may reflect these glucose metrics more closely than individual-level ones.

There are limits. Two days of recalled eating may not capture a person's usual diet. Odds ratios also do not show how much glucose would change for any one person.

The result sits alongside, but is separate from, the October 17 Arising report on a low-fat vegan diet and liver fat in type 2 diabetes. That was a small trial of a whole eating pattern. This study asks a different question, about how processed individual foods are, and cannot test any diet.

What to watch next

Studies that assign diets and follow glucose monitor data, which could show whether the processing level of foods changes blood sugar itself.

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