Effects of Cardiorespiratory Fitness on Serum Ferritin Concentration and Type 2 Diabetes: Evidence from the Aerobics Center Longitudinal Study (ACLS)

Le, Tuan D., Effects of Cardiorespiratory Fitness on Serum Ferritin Concentration and Type 2 Diabetes: Evidence from the Aerobics Center Longitudinal Student (ACLS). Doctor of Public Health (Clinical Research). May 2008, 114 pp., 12 tables, 8 figures, bibliography, 68 titles. Recent studies suggest that an elevated serum ferritin concentration is considered an independent factor associated with increased risk of type 2 diabetes and cardiorespiratory fitness (CRF) is inversely associated with diabetes. Using secondary data from Aerobics Center Longitudinal Study at the Cooper Institute, Dallas, Texas, the author explored the association between serum ferritin levels and diabetes, CRF and diabetes, and the effect of CRF on the association between serum ferritin levels and diabetes. A cross-sectional study and a longitudinal cohort study were used. In the cross-sectional study, an increased CRF level found to be associated with a decreased serum ferritin concentration and a lowered prevalence of type 2 diabetes. Participants with high ferritin levels and high triglyceride levels were 1.89 and 1.57 times more likely to have diabetes respectively. Overweight or obese individuals were 1.35 to 1.40 times more likely to have diabetes. Participants with a family history of diabetes were 3.69 times more likely to have diabetes. Participants in the highest CRF quintile levels were 40% and 15% less likely to have type 2 diabetes among persons with normal and high blood glucose, respectively. In the prospective cohort study, it was found that serum ferritin might predict the development of type 2 diabetes in males and high serum ferritin concentration levels. The incidence rate among males increased with serum ferritin quartile (ptrend [less than] 0.05). A reduction of serum ferritin concentration was associated with a reduction of diabetes risk in those participating in physical activity. It suggests physicians might use patients' serum ferritin concentrations as a marker for predicting risk for new-onset diabetes and patients should be encouraged to participate in physical activities.