ULTRA-PROCESSED FOODS AND DIABETES

It is generally believed that food processing makes starches more easily digestible and sugars more readily available, leading to a higher glycemic index (GI) and load (GL). It therefore plausible to think that NOVA Group 4 Ultra-processed foods (UPFs) would have a higher GI and GL than NOVA Group 1 Unprocessed and Minimally Processed Foods (MPFs), and that this may be a factor driving the associations found between high UPF consumption and risk of chronic diseases such as obesity, cardiovascular disease, and diabetes in observational studies.

GI, GL and UPFs

Recent research by Australian and North American researchers set out to test this hypothesis (1). GI and GL data for 2,030 foods and beverages were coded into the 4 NOVA food processing classification groups by 4 researchers in 2 pairs to ensure the best possible data matching. Contrary to their hypothesis, average GI and GL did not differ significantly across NOVA processing levels:

GI — MPF: average 54.1%; UPF: average 49.3% (P = 0.712)

GL — MPF: average 17.1 g; UPF: average 11.5 g (P = 0.890)

Regular readers of GI News know that there is a large body of compelling evidence that dietary patterns high in glycemic index and load increase the risk of developing type 2 diabetes by up to 89%, based on the results of the most recent systematic review and meta-analysis (2).

What about the evidence for UPFs in the development and management of diabetes?

UPFs and risk of developing type 2 diabetes

Dietary patterns high in UPFs are consistently associated with increased risk of developing type 2 diabetes in observational studies, with the most recent systematic review and meta-analysis (3) finding a 26% increase when the highest versus lowest quartile of UPF intakes are compared.

However, recent scientific discussions have raised concerns about whether different subtypes of UPFs may have varying effects on type 2 diabetes risk; with some potentially even having beneficial effects. For example, North American researchers recently investigated the relationship between UPF consumption and risk of type 2 diabetes in 3 large US cohorts (4):

• 71,871 women from the Nurses’ Health Study
• 87,918 women from the Nurses’ Health Study II, and
• 38,847 men from the Health Professional Follow- Up Study

They determined that

• refined breads (English muffins, bagels, rolls; White bread);
• sauces, spreads, and condiments (Cream cheese; Ketchup; Margarine; Mayonnaise (regular and low fat); Non-dairy coffee whitener; Red chili sauce; Salad dressings; Salsa; Soy sauce; Spread butter);
• artificially and sugar-sweetened beverages (Caffeinated, caffeine-free, carbonated and noncarbonated low-calorie soda; Other low-calorie Cola with caffeine; 7-up; Coke or Pepsi with caffeine & sugar; Coke or Pepsi without caffeine but with sugar; Hawaiian punch with sugar; Other carbonated beverage; Dairy coffee drinks;);
• animal-based products (Bacon; Beef, pork hotdogs; Breaded fish cakes, pieces, sticks; Chicken or turkey hot dogs; Processed meats, sausages; Salami, bologna, processed meat sandwiches); and
• ready-to-eat mixed dishes (Chowder or cream soup; French fries potatoes; Pizza; Ready-made soup from cans; Soup made with bouillon;).

were associated with higher risk of developing type 2 diabetes.

On the other hand,

• cereals (Cold breakfast cereal);
• dark and whole-grain breads (Rye, pumpernickel bread; Whole-grain bread;);
• packaged sweet and savory snacks (Breakfast bar; Brownies; Cookies, brownie, ready-made; Cookies, fat free, reduced fat; Doughnuts; Energy bars; High protein, low carb candy bars; Muffins or biscuits; Ready-made cakes; Ready-made cookies; Ready-made sweet rolls and coffee cakes; Fat-free popcorn; Fat-free, light crackers; Regular crackers);
• fruit-based products (Applesauce; Canned peaches; Canned pears; Jams, jellies, preserves, honey; Ready-made pies;); and
• yogurt and dairy-based desserts (Artificially sweetened yogurt; Flavoured yogurt without Nutrasweet; Frozen yogurt; Ice cream; Ice cream; Sherbet;)

were associated with lower risk of developing type 2 diabetes.

UPFs and the management of diabetes

To-date, no randomised controlled trials have investigated the effects of diets varying in UPF content in people with pre-existing diabetes. However, a group of North American researchers recently randomly assigned 18 healthy adults (40 to 65 years old) to kilojoule-controlled high-UPF (81% of energy) or non-UPF (0% of energy) diets and measured their insulin sensitivity and 24-h glycemic control for 6 weeks (5). There were no statistically significant (P<0.05) changes in Matsuda Index, Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), glucose Area under the Curve (AUC) or mean amplitude of glycemic excursions (MAGE) between groups at the end of the 6 week period. Needless to say, more research is needed.

What about UPFs and obesity?

Excess adiposity, in particular intra-abdominal adiposity is an underlying cause of type 2 diabetes in susceptible people (6), so dietary patterns that are associated with excess weight gain may be considered risk factors for developing the condition.

A recent review of UPFs and body weight included 9 published randomised controlled trials and determined that “the intake of HPFB [highly or ultra-processed foods and beverages] has led to increased, no change, and decreased body weight”(7). Overall, the authors concluded that “The epidemiological, randomized controlled trial, and mechanistic data linking consumption of highly processed foods and beverages with obesity risk are weak and inconsistent”.

Conclusion

It is currently common to hear that UPFs cause diabetes and that people with diabetes should be avoiding them. The current body of scientific evidence does not support these sweeping statements. Certain foods like sugar sweetened soft drinks and processed meats that are classified as UPFs are consistently associated with increased risk, but other nominally ultra-processed foods like wholegrain cereals and yoghurts are associated with decreased risk.

Scientific evidence does not currently support advice for people with diabetes or those at risk to limit NOVA Group 4 Ultra-processed foods.

Read more:

1. Basile and colleagues. Food processing according to the NOVA classification is not associated with glycemic index and glycemic load: results from an analysis of 1995 food items. Am J Clin Nutr, 2024.
2. Livesey and colleagues. Dietary Glycemic Index and Load and the Risk of Type 2 Diabetes: Assessment of Causal Relations. Nutrients. 2019.
3. Kim and colleagues. Ultra-processed food intake and risk of type 2 diabetes-a pooled analysis of three prospective cohorts of Korean adults and an updated meta-analysis. Eur J Epidemiol, 2025.
4. Chen and colleagues. Ultra-Processed Food Consumption and Risk of Type 2 Diabetes: Three Large Prospective U.S. Cohort Studies. Diabetes Care, 2023.
5. Capra and colleagues. Chemical Analysis of Controlled Diets High in and Free of Ultraprocessed Foods and Proof-of-Concept Findings. J Nutr. 2026.
6. Martin and colleagues. Estimating the Effect of Liver and Pancreas Volume and Fat Content on Risk of Diabetes: A Mendelian Randomization Study. Diabetes Care, 2022.
7. Rutigliani and colleagues. A Critical Review of the Science on “Highly” Processed Food Intake and Body Weight. Adv Nutr. 2026.