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.