Cardiorespiratory Fitness Is Inversely Associated With All-Cause Mortality In Women With Abnormal Fasting Glucose Levels

Abstract

Impaired fasting glucose (IFG) and diabetes are directly associated with mortality risk in women. The influence of cardiorespiratory fitness (CRF) on these relationships is unclear. PURPOSE To examine the associations among fasting plasma glucose, CRF and all-cause mortality in adult women. METHODS A total of 10,254 women (mean±SD: age 42±10 yrs; BMI 23±4 kg/m2) had a medical examination between 1970 and 1998, during which FG was measured. Normal glucose (NG), IFG and diabetes were defined as <100,100–125.9 and >126 mg/dL, respectively. CRF was quantified as the duration of a symptom-limited maximal treadmill exercise test. Women in the lowest fifth of the age-normalized distribution of exercise duration were classified as unfit; women in the upper four fifths of the distribution were classified as fit. Mortality surveillance was completed through December 31, 1998. Hazard ratios (HR) and 95% confidence intervals (CI) were computed using Cox regression analysis. RESULTS There were 233 deaths during a mean follow-up of 12±7 yrs and 124,073 woman-yrs of exposure. The prevalence of NG, IFG and diabetes was 75.8%, 22.8%, 1.4%, respectively. Age-adjusted death rates per 10,000 woman-yrs were 17.3,22.2, and 32.8 in women with NG, IFG, and diabetes, respectively (P-Trend =0.025). Regressed jointly, increments of 5-units in fasting glucose (HR [95% CI] =1.04 [1.0–1.10], P=0.04) and 1-minute in treadmill duration (0.95 [0.91–0.99], p < 0.001) were both associated with mortality after adjusting for age, health status, smoking, BMI, hypertension and dyslipidemia. Age-adjusted death rates forunfit and fit women were 24.7 and 13.1, respectively (p < 0.001) in women with NG, and were 46.8 and 24.5 (P=0.003) in women with IFG +diabetes combined. In multivariable analysis, fit women had a 41–45% lower mortality risk (P=0.01) than unfit women in the NG as well as the IFG +diabetes group. CONCLUSIONS The mortality risk associated with abnormal fasting glucose was substantially lower in fit compared with unfit women. Supported by NIH Grant AG06945 and HL62508