Impact of cardiorespiratory fitness and diabetes status on cardiovascular disease and all-cause mortality: An NHANES retrospective cohort study

High cardiorespiratory fitness (CRF) is associated with decreased mortality in people with pre-diabetes (pre-DM) and diabetes mellitus (DM); however, the degree to which CRF attenuates the risk of CVD-related and all-cause mortality is unclear. Study objective We examined the impact of CRF status on CVD-related morbidity and all-cause mortality in non-DM, Pre-DM, and DM populations. Design and setting 13,968 adults from the US National Health and Nutrition Examination Survey (NHANES III) were stratified into non-DM, pre-DM, or DM groups based on HbA1c levels. VO2Max was calculated using the Fitness Registry and Importance of Exercise: A National Database (FRIEND) equation. Participants Participants were categorized into tertiles of VO2Max; first VO2Max tertile was the lowest VO2Max and third VO2Max tertile was the highest. Main outcome measure(s) Cox regression was used to analyze the relationship between glycemic levels, VO2Max, and CVD-related and all-cause mortality. Results Those with DM in the highest fitness tertile had CVD (HR 0.13; 95 % CI 0.06, 0.27; p < 0.0001) and all cause (HR 0.28; 95 % CI 0.21, 0.38; p < 0.0001) mortality rates as low or lower than those with pre-DM (CVD HR 1.02; 95 % CI 0.78, 1.33 p < 0.892; all cause HR 0.96; 95 % CI 0.83, 1.12; p < 0.5496) or non-DM (CVD HR 0.65; 95 % CI 0.52, 0.80; p < 0.0001; all cause HR 0.61; 95 % CI 0.55, 0.68; p < 0.0001) at lower fitness levels. Regardless of DM status, there was lower all-cause mortality with higher CRF levels. Conclusions Higher fitness levels in DM individuals are associated with total and CVD mortality rates as low or lower than those without DM with lower fitness.