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Fruit Intake May Reduce Risk of Developing Type 2 Diabetes, Study Shows

Fruit salad

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Key Takeaways:

  • Researchers investigated how fruit and juice impact the risk of developing type 2 diabetes.
  • Study participants who ate two to three servings of fruit daily had a 36% lower odds of having diabetes at five years of follow-up, and fruit intake was associated with better measures of glucose tolerance and insulin sensitivity.
  • Whole fruit, but not fruit juice, may play a role in reducing diabetes risk due to its fiber and vitamin content. 

Type 2 diabetes (T2D) is commonly known as a lifestyle disease since it can be impacted by dietary choices and physical activity levels. A diet rich in vegetables and fruit is recommended to reduce diabetes risk, but some people worry about the dietary impact of the sugar in fruit and juice

In a recent study published in The Journal of Clinical Endocrinology & Metabolism, researchers looked at the link between fruit, juice, and the risk of developing type 2 diabetes. 

A past meta-analysis showed a reduced risk for diabetes in people who ate more fruit. Past cohort studies also show that a higher consumption of blueberries, grapes, and apples was associated with a significantly lower risk of T2D, while consumption of juice was associated with a higher risk.

The aim of this present study was to look specifically at how fruit and juice impact measures of insulin resistance and beta-cell dysfunction. The researchers also investigated how fruit intake impacts the risk of developing diabetes at five and 12 years of follow-up.

What Did the Study Look At?

This study drew data from a national population-based survey of Australian adults between 1999 and 2000, with follow-up in 2004 and again in 2011. The mean age of the 7,675 study participants was 54 years old.

Data was available for 60% of these participants at the five-year follow-up and 46% of the original participants at the 12-year follow-up.

Participants were given a food frequency questionnaire, which assessed their total fruit intake, individual fruits, and fruit juice.

Primary outcomes included measures of fasting plasma glucose, two-hour post-load plasma glucose, and beta-cell function.

What Did the Study Find?

For this population, the total fruit intake was 162 grams per day, the equivalent of two medium-sized pieces of fruit. The most commonly consumed fruits were apples (23%), bananas (20%), and oranges and other citrus fruits (18%).

Nicola Bondonno, PhD

We found a correlation between fruit intake and markers of insulin sensitivity, meaning that people who consumed more fruit had to produce less insulin to lower their blood glucose levels.

— Nicola Bondonno, PhD

The study results showed that higher total fruit intake was associated with better measures of glucose tolerance and insulin sensitivity. Plus, eating fruit was associated with lower odds of developing T2D after five years of follow-up. There were also lower odds of T2D at 12 years, but the associations were not statistically significant.

“We found a correlation between fruit intake and markers of insulin sensitivity, meaning that people who consumed more fruit had to produce less insulin to lower their blood glucose levels,” explained Nicola Bondonno, PhD, Postdoctoral Research Fellow at the Institute for Nutrition Research at Edith Cowan University in Joondalup, Australia, and one of the study's authors. 

“This is important because high levels of circulating insulin can damage blood vessels and are related to diabetes, high blood pressure, obesity, and heart disease.”

Bondonno’s study showed that those who consumed around two servings of fruit per day had a 36% lower risk of developing type 2 diabetes mellitus over the next five years compared to those who consumed less than half a serving of fruit per day.

“Interestingly,” adds Bondonno, “we did not see the same patterns for fruit juice, indicating that we should focus on consuming whole fruits.”

Choose Whole Fruit Instead of Juice

People often assume that since juice is made from fruit, it must be just as nutritious as fruit. But studies show that’s often not the case.

“When you juice a fruit, you remove most of the pulp, and therefore a lot of the fiber,” says Bondonno. “There are many benefits to consuming fruit fiber. Not only does it help you feel fuller for longer, but it also blunts the rapid rise in blood sugar that comes with consuming foods or beverages containing sugar, and it is important for gut health.”

“Fruit is a powerhouse of glucose-managing benefits,” says dietitian Toby Smithson, MS, RDN, CDCES, FAND, a diabetes lifestyle expert with Diabetes Everyday and author of "Diabetes Meal Planning and Nutrition for Dummies." 

“Whole fruit also tends to satisfy the appetite,” says Smithson. “Fruit juice raises blood sugar more quickly, tends to contain less fiber, and does not satisfy the appetite as effectively as whole fruit.”

How is Fruit Protective Against Diabetes?

The reason why fruit helps prevent T2D is multifaceted. It’s likely a combination of fruit being low in calories, but high in protective fiber, vitamins, minerals, and phytochemicals.

The study found that apples were a commonly eaten fruit that may provide even greater protection against T2D. Apples contain phytochemicals called flavonoids, which help improve insulin sensitivity, potentially by decreasing apoptosis (cell death) and promoting the proliferation of pancreatic beta-cells. 

There’s a persistent belief that “sugar causes diabetes” and people think that sugary fruit contributes to this problem. This study highlights why that’s just not the case.

“Evidence shows that the health risks from sugars, such as tooth decay and unhealthy weight gain, are related to consuming ‘free sugars,’ not from eating sugars that are naturally present in fruits,” says Bondonno.

Nicola Bondonno, PhD

Evidence shows that the health risks from sugars, such as tooth decay and unhealthy weight gain, are related to consuming “free sugars,” not from eating sugars that are naturally present in fruits.

— Nicola Bondonno, PhD

“Free” sugars and “added” sugars include white or brown sugar, syrups, and honey, whether on their own or added to foods or beverages, such as candy, soda, and ice cream.

Smithson explains that T2D begins as “insulin resistance” where blood sugar levels remain high after eating carbohydrate-rich foods because the cells that should absorb glucose from the bloodstream are not responding to insulin.

“Sugar does not cause diabetes, but excess added/free sugar and concentrated sweets can increase the risk,” says Smithson. “Fruit contains fabulous fiber that helps blunt blood sugar spikes.”

To further minimize spikes in blood sugar, Smithson recommends combining fruit with a source of protein or fat, as these nutrients will help slow down the absorption of the sugar that's consumed.

What This Means For You:

Enjoy three servings of whole fruit daily to lower your risk of developing type 2 diabetes. The benefits of fiber, vitamins, minerals and phytonutrients found in fruit outweigh any concerns about eating a food that contains natural sugar. 

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