Combined effects of maximal oxygen uptake and glucose status on mortality: The Prospective KIHD cohort study

OBJECTIVE: To examine the combined effects of cardiorespiratory fitness (CRF) and prediabetes or diabetes on cardiovascular and noncardiovascular mortality. PATIENTS AND METHODS: This prospective study evaluated a population‐based cohort of 1562 men aged 42–60 years at baseline (1984–1989). We utilized maximal oxygen uptake (VO(2max)) for assessing aerobic capacity and CRF in the cohort and stratified participants into six groups according to both their glucose status (diabetes, prediabetes, or no diabetes) and whether they were below‐ or above‐median VO(2max). Deaths in the cohort were recorded till December 31 2016. Cox regression was used to calculate hazard ratios (HR) with 95% confidence intervals (CI) for cardiovascular and noncardiovascular mortality. Smoking, alcohol consumption, BMI, blood pressure, cholesterol, diagnosis of ischemic heart disease, and socioeconomic status served as covariates in the mortality analyses. RESULTS: During the follow‐up (mean 24.2 years), 341 men died from cardiovascular and 468 men from noncardiovascular causes. When compared to men with no diabetes and above‐median VO(2max), the presence of either diabetes (HR = 4.10, 95% CI: 2.27–7.40) or prediabetes (HR = 2.10, 95% CI: 1.18–3.73) combined with below‐median VO(2max) increased the risk of cardiovascular death. Noncardiovascular mortality was increased by low oxygen uptake in men with prediabetes (HR = 2.24, 95% CI: 1.30–3.84), and among men with diabetes, the increase was not statistically significant (HR = 1.99, 95% CI: 0.91–4.32). CONCLUSIONS: Cardiorespiratory fitness modifies the risk of death related to prediabetes and diabetes. This highlights the importance of CRF assessment and interventions to support the uptake of regular physical activity among aging men with disturbed glucose metabolism.