Takeaway: risk rose with intake and became statistically significant only at the two highest consumption levels.

Why might a sugar cause inflammation?

Neu5Gc is produced naturally by most mammals, but humans lost the ability to make it after an ancient mutation in the CMAH gene. The sugar still enters the body through food — mainly red meat, with smaller amounts in dairy.

After absorption, the body can incorporate Neu5Gc into its own tissues. Because humans do not produce it, the immune system may flag it as foreign. Scientists call it a xeno-autoantigen: a foreign substance built into body tissues that can provoke an immune reaction.

The immune system responds by producing antibodies against Neu5Gc. The resulting prolonged immune activity, termed xenosialitis, has previously been linked to cardiovascular disease and cancer. Researchers suspect this persistent inflammation could also damage insulin-producing cells or tissues that respond to insulin — but no large prospective study had tested this before.

"Our findings support chronic inflammation as a specific mechanism linking red meat consumption with T2D, partly beyond the amount of red meat a person eats and partly independent of body fat," Dr. Fezeu said.

Takeaway: the proposed mechanism is immune reaction to a sugar the human body cannot make itself.

How much does body weight explain?

Obesity accounted for only about 13% of the association between meat-derived Neu5Gc and type 2 diabetes, according to the researchers' estimates. The link weakened after body mass index was considered but remained statistically significant.

This suggests factors unrelated to excess weight may drive much of the observed connection. Still, the study cannot confirm that inflammation is the mechanism; additional research is required.

Why did dairy behave differently?

Despite containing Neu5Gc, dairy products showed no association with increased diabetes risk. The researchers attribute this to the much smaller amounts of Neu5Gc in cow's milk compared with beef and lamb.

When the researchers counted Neu5Gc from all dietary sources combined, the highest intake group had a 37% greater diabetes risk — weaker than the meat-only figure, indicating red meat drove the association.

"The association between Neu5Gc and T2D may depend on its dietary source, with meat-derived Neu5Gc showing a stronger association with T2D risk than total dietary Neu5Gc," Dr. Fezeu said. "There may be differences between sources, or other components of red meat may contribute."

What are the limitations?

The findings carry important caveats:

• The results are preliminary and not yet validated; estimates could change in the final analysis.
• The observational design cannot prove Neu5Gc causes diabetes.
• When the analysis accounted for total red meat consumed, the association weakened and lost statistical significance — so the sugar itself may not be responsible.
• Neu5Gc intake was estimated from food records, not measured directly, and dietary changes during follow-up were not captured.

The team plans to study how Neu5Gc interacts with other red meat components, including heme iron, and to directly measure anti-Neu5Gc antibodies in large cohorts to test the xenosialitis mechanism in humans.

Dr. Fezeu suggested future research should explore whether favoring poultry or plant-based proteins over beef and lamb — the meats highest in Neu5Gc — could help prevent type 2 diabetes.

The study offers a plausible new mechanism, not a verdict.