Background: Sedentary lifestyle, obesity, and impaired glucose regulation are associated with the risk of type 2 diabetes. However, the joint associations of these risk factors are not known.
Methods: We prospectively followed up 2017 Finnish men and 2352 Finnish women aged between 45 and 64 years without a history of known or newly diagnosed diabetes at baseline. Single and joint associations of physical activity, body mass index (BMI), and blood glucose levels with risk of type 2 diabetes were examined using Cox proportional hazards models.
Results: During a mean follow-up of 9.4 years, there were 120 incident cases of type 2 diabetes. After adjustment for confounding factors (age, study year, sex, systolic blood pressure, smoking, and education), physical activity was found to be inversely associated with the risk of type 2 diabetes. This association was persistent in subjects with (1) both obesity and impaired glucose regulation, (2) either obesity or impaired glucose regulation, and (3) a normal BMI and glucose regulation. Similarly, the multivariate-adjusted positive association between BMI and risk of type 2 diabetes was consistently observed. Obesity in subjects who reported being inactive and had normal glucose levels was associated with an increased risk of diabetes compared with a normal BMI in subjects who reported being active and had impaired glucose regulation.
Conclusions: Increasing physical activity can reduce the risk of type 2 diabetes. The protective effect of physical activity was observed in subjects with an excessive BMI and elevated glucose levels. Physical activity and weight control are critical factors in diabetes prevention in subjects with both normal and impaired blood glucose regulation.