Regularly eating fried potato chips, a delicacy for many, may increase a person's risk of developing Type 2 Diabetes, according to a new study published in the British Medical Journal (BMJ).
ALSO READ: Why your potato meal comes at a higher cost
However, preparing potatoes differently, such as boiling, baking, or mashing, does not substantially increase the risk, according to the researchers, who published their findings in early August.
ALSO READ: Shun junk food for good health
The observational study shows that consuming three servings of chips a week was linked to a 20 per higher chance of type 2 diabetes. In comparison, eating similar amounts of potatoes prepared by other methods showed no association with an increased risk.
The researchers found that replacing potatoes with whole grains lowered the risk of developing type 2 diabetes, while substituting them with white rice was linked to a higher risk.
Potatoes provide fiber, vitamin C, and magnesium, but their high starch content and glycemic index have long raised concerns about their impact on blood sugar.
ALSO READ: Fast food culture may be convenient, but it’s affecting public health
How did researchers link chips to diabetes?
Until now, little attention had been given to how cooking methods or substitution with other foods might change their health effects.
To investigate further, the team analyzed dietary and health data from over 205,000 US health professionals who participated in three large studies between 1984 and 2021. None of the participants had diabetes, heart disease, or cancer at the start of the research, and they filled out detailed food questionnaires every four years.
Over 40 years of follow-up, 22,299 of the participants were diagnosed with type 2 diabetes.
After adjusting for lifestyle and dietary factors linked to diabetes risk, the researchers reported that each additional three weekly servings of total potato intake was associated with a 5 per cent increase in type 2 diabetes rates.
For chips, the rise was much higher at 20 per cent. Baked, boiled, or mashed potatoes, however, showed no link to the disease.
The analysis also looked at what happens when potatoes are replaced with other staple foods. Replacing three weekly servings of total potatoes with whole grains reduced type 2 diabetes rates by 8 per cent.
Substituting baked, boiled, or mashed potatoes with whole grains lowered the risk by 4per cent, and replacing chips with whole grains cut the rate by 19 per cent.
By contrast, replacing potatoes or baked, boiled, or mashed potatoes with white rice was associated with a higher risk of type 2 diabetes.
Does eating potatoes cause diabetes?
The authors cautioned that this was an observational study, meaning it could not prove direct cause and effect potato intake and type 2 diabetes. Unmeasured lifestyle or dietary factors could still have influenced the results. They also noted that most participants were health professionals of European ancestry, so the findings may not extend to more diverse populations.
"Our findings show that the association between potato intake and type 2 diabetes risk depends on the specific foods used as replacement. The findings also align with current dietary recommendations that promote the inclusion of whole grains as part of a healthy diet for the prevention of type 2 diabetes,” the researchers said.
They noted that preparation methods and replacement foods should guide public health advice. With their relatively low environmental impact, baked, boiled, or mashed potatoes can form part of a healthy and sustainable diet. Whole grains, however, should still be a priority, and further studies involving diverse populations are needed.
Health risks of overeating chips
In an interview with The New Times, Hyguette Irambona, a nutritionist at Gardens for Health International, a nonprofit, said chips raise the risk of diabetes because of how they affect blood sugar and insulin.
She added that, like other carbohydrates, potatoes are converted into glucose to provide energy, but foods high in simple sugars cause blood sugar to rise more quickly.
Irambona explained that the pancreas responds by producing insulin, which helps the body use that sugar.
"If this happens daily with foods like chips, the body gradually becomes less sensitive to insulin," she said. "As a result, blood sugar remains high in the bloodstream, and the pancreas struggles to control it. That’s how overconsumption can lead to diabetes.”
She noted that deep frying adds another layer of risk, explaining that chips don’t just raise blood sugar; they also contain unhealthy fats that increase bad cholesterol. That combination puts people at risk of heart disease and worsens insulin resistance.
She explained that insulin resistance can have other health problems beyond diabetes, saying it contributes to aging, acne, and even mental health issues.
The way chips are commonly prepared in Rwanda adds further concern since oil is reused multiple times. Repeated use produces free radicals, harmful compounds that accumulate in the body. Over time, research has shown they can increase the risk of cancer, she added.
Irambona advised consuming chips in moderation, explaining that occasional intake is fine, but eating them daily stresses the body and eventually reduces its ability to manage sugar and unhealthy fats effectively.
"No food is entirely good or bad, so how often we eat matters most," said the nutritionist. "Almost everything should be taken in moderation, because there is no single food that cures or harms completely. Even porridge made with soy, maize, sorghum, and sugar raises blood sugar, and the same applies to rice, spaghetti, or potatoes. Chips are particularly risky because they combine sugar and unhealthy fats in one plate,” Irambona said.