New research being presented at the Annual Meeting of The European Association for the Study of Diabetes (EASD) in Milan, Italy (Sept 28 – Oct 2), suggests that higher levels of moderate-to-vigorous physical activity (MVPA) are associated with a substantially lower risk of developing type 2 diabetes (T2D), particularly among younger adults.
Over a median follow-up of nearly eight years, the study found that adults younger than 63 years in the lower level exercise group, who did a median of 121 minutes of MVPA per week, had more than double the risk of developing T2D compared with those in the higher-MVPA group, who did a median of 409 minutes per week. In contrast, among adults aged 63 years and older, lower levels of MVPA were associated with a 65% higher relative risk of developing T2D.
However, because older adults have a higher overall risk of T2D, encouraging more adults to be physically active could prevent more cases of T2D among older people.
"The takeaway message is that all adults should be encouraged to be as active as they can, as more physical activity is linked to a lower risk of type 2 diabetes," said Dr Diana van Heemst from Leiden University Medical Centre, who led the research. "However, at the population level, we may see the greatest reduction in the number of new cases of type 2 diabetes among older adults. Our findings do not support different MVPA timing recommendations for specific population groups."
Current public health guidelines recommend that adults do at least 150 minutes a week of MVPA that is intense enough to leave you slightly out of breath such as brisk walking, running or cycling.
However, the potential benefits of MVPA for preventing and managing T2D may vary by age and sex, reflecting differences in metabolism and physiological responses to exercise. In addition, underlying metabolic conditions, such as obesity and dyslipidaemia (unusually high levels of cholesterol and other fats in the blood), may influence the relationship between physical activity and the risk of developing T2D.
To find out more, researchers from Leiden University Medical Centre in the Netherlands, set out to look at how both exercise levels (lower vs higher) and timing (late-day vs early-day) affected the risk of developing T2D.
They also examined whether age, sex, and underlying metabolic diseases—including prediabetes, dyslipidaemia, and high blood pressure—modified these associations between exercise and T2D.
The study included data from 87,975 adults without a history of diabetes who were taking part in the UK Biobank study between February 2013 and December 2015. The average age was 63 years, 57% were female, and 97% were white.
The study participants wore an accelerometer device on their wrist for seven consecutive days to record their typical exercise levels. Exercise levels were categorised as lower or higher based on the average number of minutes of weekly MVPA in each age group. This approach helped avoid disproportionately classifying older participants as having lower levels of physical activity.
During an average follow up of 7.7 years, 2,140 participants (2.4%) developed T2D—including 748/44,020 participants in the higher volume exercise group (who had an overall median of 409 minutes MVPA/week) and 1,392/43,955 participants in the lower volume exercise group (who had an overall median of 121 minutes).
The analysis found that participants in the lower MVPA group, who did not meet the recommended 150 minutes per week, had twice the relative risk of developing T2D compared with those in the higher MVPA group, after adjusting for potential confounders, including age, sex, ethnicity, education, deprivation, smoking status, sleep duration and family history of diabetes.
Additionally, adults who did most of their exercise later in the day, from 1pm to midnight, had a 10% lower relative risk of T2D than those who exercised earlier, from 5am to before 1pm.
Benefits of physical activity greatest in older adults
Importantly, the analysis found that both age and underlying pre-diabetes influenced the relationship between physical activity and T2D risk.
Among younger adults (aged younger than the average population age of 63 years), lower levels of MVPA were associated with more than twice the relative risk of developing T2D compared with higher levels of MVPA. In contrast, among older adults (older than 63 years), lower levels of MVPA were associated with a 65% higher relative risk of T2D.
The time of day also appeared to matter more for younger adults. Exercising later in the day was associated with a 23% lower risk of T2D among younger adults, compared with a 4% lower risk among older adults.
The association was also stronger among people without prediabetes, with lower levels of MVPA associated with more than twice the relative risk of developing T2D compared with higher levels. In contrast, among those with prediabetes, lower levels of MVPA were associated with a 54% higher relative risk of developing T2D.
When the analysis comparing lower and higher levels of MVPA was broken down into five-year age groups, the relative risk of developing T2D declined with increasing age. However, the T2D incidence rates difference increased substantially with age in the overall population, meaning that the absolute benefit of physical activity was greater in older age groups.
For example, the decrease in relative risk estimates comparing lower with higher MVPA levels with increasing age was more pronounced in women than in men. Among women, the difference in T2D incidence rates remained relatively stable across age groups. Among men, the absolute difference in incidence rates was larger and increased steeply with age.
According to author Qiuyu Feng from Leiden University Medical Centre, "Our findings underscore why it is important to look at both relative and absolute risk when considering the public health impact of physical activity. Relative risk alone does not capture how much physical activity could help reduce the number of cases in different population groups."
The researchers note several limitations to the study, including that the study population was not representative of the UK population, as UK Biobank participants are known to be generally healthier, wealthier and better educated than the wider population. In addition, pre-diabetes status was assessed several years before physical activity was measured using accelerometers and may have changed over time, which could have underestimated the findings.
