Could Your Saliva Predict Diabetes Risk? Study Finds Out - Video

A new Cornell University study brings additional clarity to the relationship between Type 2 diabetes and genes that express a salivary enzyme that breaks down starch.

It was previously known that people with more copies of the genes that express salivary amylase (called AMY1) produce more salivary amylase enzyme. The new paper, published in PLOS One, supports the idea that having more copies of the AMY1 gene may be protective against Type 2 diabetes, though additional long-term studies are needed to prove the theory.

If researchers do eventually prove a clear association between AMY1 copy number and diabetes, it could lead to genetically testing people at birth to predict their susceptibility.

Researchers collected measurements from study participants of amylase activity very early in the morning after fasting and in the evening. They found that morning readings were much lower than they were in the evenings.

When they compared participants, they found that salivary amylase activity was higher for each additional copy of AMY1 in those with Type 2 diabetes or prediabetes, compared to those without either.

The findings have led Angela Poole, assistant professor of molecular nutrition, to suspect that a higher copy number of AMY1 genes may be protective, though more study is needed to verify it.

Since amylase breaks down starch into sugars, common sense would suggest that a higher AMY1 copy number would increase blood glucose and be detrimental to people with Type 2 diabetes. Poole suspects that during chewing of starch, the body senses the glucose, and it causes people with a higher AMY1 copy number to release insulin sooner, leading to a protective effect. Gut microbes may also play a role.

“I suspect that people with a lower copy number are at higher risk for Type 2 diabetes,” Poole said. But she added, it also depends on how much starch they eat.

Reference: Devarakonda SLS, Ren J, Poole AC (2025) The association between salivary amylase gene copy number and enzyme activity with type 2 diabetes status. PLoS One 20(7): e0324660. https://doi.org/10.1371/journal.pone.0324660