Delving into three decades' worth of medical data from nearly 200,000 patients, the Harvard researchers estimated the participants average gluten intake and probed which patients developed type 2 diabetes, the most common type of diabetes, over time.
Gluten is in wheat, rye and barley, and is found in many pastas, breads and cereals.
The investigators found that study participants who ate the least amount of gluten had a somewhat higher risk of developing diabetes over time.
This finding suggests that there might be a link between people's gluten consumption and their risk of diabetes, the researchers said.
For the new research, which was presented at the American Heart Association's Epidemiology and Prevention / Lifestyle and Cardiometabolic Health 2017 Scientific Sessions, researchers analyzed three long-term studies consisting of almost 200,000 people.
To date, no scientific studies have demonstrated any health benefits that accrue from a gluten-free diet for the vast majority of people who do not suffer from Celiac disease (which affects one percent of the population in the US) or gluten intolerance.
The team approximated the gluten consumption for 199,794 individuals enrolled in three long-term studies: the Nurses' Health Study (NHS) I and II, and the Health Professionals Follow-up Study (HPFS). But experts say this is likely due to cutting out junk food and not about the actual gluten.
"It's not clear whether gluten itself is the protective factor, or whether its other foods where gluten is present that influence diabetes risk reduction".
One possible explanation is that the people who consumed more gluten also ate more fiber, which, as previous research suggested, may help to lower a person's diabetes risk.
The study does not prove that limiting gluten somehow causes diabetes, according to Lauri Wright, a spokeswoman for the Academy of Nutrition and Dietetics.
"The health consequences of following a gluten-free diet composed primarily of processed foods can lead to weight gain and detrimental long-term consequences associated with low fiber intake", she said.
"The rise of popularity of the gluten-free diet is a double-edged sword for people with a medical necessity for it", Alice Bast, chief executive officer of the patient advocacy group Beyond Celiac, told Healthline.
Image bank gluten-free images are really weird.
Those who have a sensitivity to the protein are often diagnosed with celiac disease.
Only foods and beverages with a gluten content less than 20 parts per million are allowed.
Eating a gluten-free diet isn't healthy if you can eat gluten without discomfort, say researchers.