Higher fitness levels reduce the risk of diabetes
A 20-year study demonstrates that higher levels of cardiorespiratory fitness (CRF) reduce the risk for developing prediabetes or diabetes. This is the longest study conducted in this area and provides strong evidence that supports the commonly accepted view that fitness is beneficial in reducing the risk for prediabetes and diabetes.
Previous studies demonstrating this link have been limited for several reasons, including use of a largely male population, measurement of fitness over a limited duration (5–7 years) or measurement of fitness at varying intervals prospectively. However, in this new research, the authors used data from the Coronary Artery Risk Development in Young Adults (CARDIA) study to objectively and rigorously analyse the link between CRF and development of either prediabetes or diabetes over a 20-year period. The study also adjusted for changes in body mass index over time.
The CARDIA study included 4373 subjects from four US communities who were balanced on age, race, sex and educational attainment. CRF was assessed prospectively by treadmill exercise testing at baseline (Year 0: participants aged 18–30 years), early adulthood (Y7: the same participants now aged 25–37 years) and again at middle age (Y20: now aged 38–50 years). Development of prediabetes/diabetes was ascertained during scheduled visits (at Y0, Y7, Y10, Y15, Y20, and Y25).
The study found that when using treadmill exercise testing to measure CRF, an 8–11% higher fitness level reduced the risk for developing prediabetes or diabetes by 0.1%. For context, achieving this higher level of fitness required either vigorous physical activity for 30 minutes daily, 5 days per week or moderate physical activity for 40 minutes daily, 5 days per week. While the CARDIA study found that the overall reduction in risk for prediabetes/diabetes was modest at the individual level, these changes remain significant at the population level where small changes in a large number of individuals may lead to large absolute reduction in prediabetes/diabetes.
This study is clinically relevant as it provides evidence to support the commonly accepted view that fitness is beneficial in reducing the risk for prediabetes and diabetes. As this benefit remained significant even when adjusting for BMI, it is important that healthcare professionals continue to encourage people to exercise to reduce their risk of developing prediabetes and diabetes.
Chow L et al. Twenty year fitness trends in young adults and incidence of prediabetes and diabetes: the CARDIA study. Diabetologia 2016; DOI 10.1007/s00125-016-3969-5