Relationship between physical fitness and physical activity and type 2 diabetes mellitus

The purpose of this study is to investigate the impact of physical fitness and physical activity on the development of Type 2 diabetes mellitus (t2dm). Physical activity can affect t2dm directly through mechanisms such as changes in insulin sensitivity (Yamanouchi, 1995; Mayer-Davis, 1998; Regensteiner, 1991) and indirectly through improvements in body composition and weight loss (Tremblay, 1991; Wood, 1991; Pavlou, 1989). Since fitness and activity are not strongly related to each another (Leon, 1981; Siconolfi, 1985; Jacobs, 1993), the independent effects of both on the development of t2dm needed to be examined. Therefore, it is hypothesized that, compared to those less fit, those who are more fit will be less likely to develop t2dm. Similarly, it is hypothesized that those who are more physically active will be less likely to develop t2dm than those who are less active.;The current population consists of 3575 women and 3284 men enrolled in the Aerobics Center Longitudinal Study conducted at the Cooper Clinic in Dallas, Texas. Each participant completed at least one medical examination and either returned to the clinic for a second exam or sent back a mail survey. The exam involved filling out a medical history and health habits questionnaire (including physical activity habits), completing a maximal treadmill test, and having blood drawn in order to measure fasting glucose. A major strength of this prospective study is the existence of objective measures of physical fitness and t2dm in a large population of men and women.;In women and men, physical fitness appeared to be protective against t2dm development. For each additional minute on a treadmill test a woman's risk for t2dm decreased by seven percent (P = 0.11) and a man's risk decreased by 10 to 12% (P ≤ 0.03). Also, in men, physical activity consistently (although not significantly) appears to prevent t2dm development.;This study suggests that both physical fitness and physical activity may each be protective against the development of t2dm. More research needs to be conducted to determine the benefits of moderate levels of activity in the prevention of t2dm.