New study finds physically fit people are less likely to develop type 2 diabetes

by Barbara Hewitt on May 19, 2016

A long term study in the United States has found that people with higher levels of physical fitness are less likely to develop type 2 diabetes.

It is well known that exercise plays an important part in fending off and also managing type 2 diabetes but this 20 year study researchers from the University of Minnesota set out to see if exercise could prevent prediabetes and type 2 diabetes.

They found that higher levels of cardiorespiratory fitness maintained or increased from early adulthood to middle age significantly reduce an individual’s risk of developing prediabetes and diabetes.


More importantly, they also found that the association between incremental increases and objective physical fitness and prediabetes and type 2 diabetes risk held even after taking into account factors such as body mass index (BMI).

According to Lisa Chow from the university’s division of diabetes, endocrinology, and metabolism, although the results were modest on an individual level, when they are considered on a population level, they really emphasize the importance of fitness and that improving fitness through physical activity can reduce prediabetes and diabetes.

She pointed out that previous studies were limited for several reasons, including use of a largely male population, measurement of fitness over a limited duration of five to seven years or measurement of fitness at varying intervals prospectively.

For this research the team studied 4,373 black and white participants from the Coronary Artery Risk Development in Young Adults (CARDIA) study over a longer period of 20 years.

The participants, who were recruited in 1985 and 1986 when they were aged 18 to 30 years, completed baseline treadmill exercise testing to determine cardiorespiratory fitness. This was followed by repeat testing in year seven of the study, when they were aged 25 to 37 years, and again at year 20, when they were aged 38 to 50 years.

By year 25, some 44.5% of participants developed prediabetes and 11.5% developed type 2 diabetes. Participants who developed prediabetes or diabetes by year 25 were more likely to be older, of black race, and male than those who did not and were more likely to take blood pressure medication, smoke, and have a higher BMI, among other factors.

The study found that an 8% to 11% higher fitness level on treadmill exercise testing reduced the risk for developing prediabetes or diabetes by 0.1%. This is equivalent to either vigorous physical activity for 30 minutes daily five days per week or moderate physical activity for 40 minutes daily five days per week.

The researchers put forward a number of hypotheses as to how continued fitness may reduce the risk of developing prediabetes and diabetes, including the effect of exercise on visceral fat, the anti-inflammatory effect of exercise, and its impact on insulin sensitivity.

However, Chow believes that there may be more than one mechanism at play. “I think it’s all of them, and I think for different people it might be different, in the sense that some people when they exercise tend to lose more fat, whereas other people when they exercise tend to have a better cardiac response,” she said.

“I think there is a real need to personalise fitness to individuals, but, of course, that’s beyond the scope of this study,” she added. Looking ahead, she said that the US National Institutes of Health is very interested in how people will respond to a given exercise intervention in an attempt to see how different people respond to the same dose of exercise.

The opinions expressed in this article do not necessarily reflect the views of the Community and should not be interpreted as medical advice. Please see your doctor before making any changes to your diabetes management plan.

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