The IDES_2 (Italian Diabetes and Exercise Study 2) trial evaluated the effects of a 4-week structured counselling intervention to increase moderate-to-vigorous physical activity (MVPA) and reduce sedentary time in 300 adults with type 2 diabetes over a 3-year follow-up (Balducci et al, 2019). The intervention was previously shown to increase measures of physical fitness and lower body strength despite only modest increases in MVPA (6.4 minutes per day) and reductions in sedentary time (0.8 hours per day).
This prespecified subanalysis of IDES_2 was conducted to determine the effects of improved physical fitness on cardiometabolic risk profiles. Mean changes in MVPA, sedentary time, VO2max, muscle strength, and cardiovascular risk factors and scores were assessed at least annually for the 267 study completers, and were compared irrespective of study arm (IDES intervention or standard care).
Three-year changes in VO2max were divided into quartiles, with means that ranged from a reduction of 2.2 to increases of 0.8, 2.9 and 7.0 mL/min/kg. Over the follow-up, mean 10-year coronary heart disease (CHD) risk scores (UKPDS risk engine, in %) increased by 5.57, 3.83, 2.35 and 1.75 in quartiles 1–4, respectively. Multivariate regression analysis showed that increases in VO2max independently predicted increases in HbA1c, diastolic blood pressure, HDL-cholesterol, and 10-year CHD and stroke risk scores. Similar findings were observed for increases in lower body strength.
Interestingly, these associations remained significant after adjusting for changes in BMI, waist circumference and body composition, and even after further adjustments for MVPA and sedentary time.
Thus, the authors conclude that sustained improvements in physical fitness produced by modest increases in MVPA and reductions in sedentary time are associated with a better cardiometabolic risk profile. More importantly, the results suggest that the contribution of increased fitness to improvements in cardiovascular risk factors and scores may be supplemental to those brought about both by changes in adiposity and body composition and by increases in MVPA and reductions in sedentary time.