Associations of cardiorespiratory fitness and parental history of diabetes with risk of type 2 diabetes

Aims: We examined the independent and joint associations of cardiorespiratory fitness (CRF) and parental diabetes history on type 2 diabetes risk. Methods: A cohort of 11,627 individuals aged 20-79 years was free of baseline diabetes, cardiovascular disease, and cancer. We measured CRF using a maximal treadmill exercise test, and parental diabetes by a medical history questionnaire. Results: During an average 5.5 year follow-up, 572 cases of type 2 diabetes occurred. Compared with the least fit 20%, the multivariate hazard ratio (HR) (95% CI) was 0.59 (0.43-0.83) for the middle fit 40%, and 0.53 (0.38-0.75) for the high fit 40%. Those with parental diabetes had a 1.40-fold higher risk for developing type 2 diabetes. In combined analyses using fit, no parental diabetes as the referent, unfit with no parental diabetes was 1.79 (95% CI 1.25-2.57) times more likely to develop type 2 diabetes, while the risk with parental diabetes was 1.41 (95% CI 1.12-1.78) and 2.37 (95% CI 1.25-4.49) times higher in the fit and unfit, respectively. Conclusions: While high CRF did not fully attenuate the risk of diabetes associated with parental diabetes, being fit reduces diabetes risk regardless of parental history. (C) 2011 Elsevier Ireland Ltd. All rights reserved.