Lifestyle modifications with diet and exercise have always been an integral part of preventing and managing type 2 diabetes (T2DM). Although aerobic exercise is the principal recommendation for physical activity in diabetic patients, weight and resistance training have shown proven benefits in improving glycemic control in individuals with T2DM. Castaneda and colleagues showed that progressive resistance training over the course of 16 weeks lowered HbA1c from 8.7 to 7.6 and required medication dose reductions in 72% of the study group with T2DM.1 Also, Dunstan and colleagues demonstrated the statistically significant decreases in glucose and insulin areas under the curve for diabetics participating in circuit weight training three times a week for 8 weeks over the control group.2 On the basis of such results, the ADA guidelines now recommend that T2DM patients engage in weight/resistance training at least twice a week unless contradindicated.3 Despite the benefit in individuals with T2DM, there are limited studies on the effect of weight and resistance training in preventing T2DM.4
Grøntved and colleagues sought to determine the effect of weight training as an independent factor on reducing the risk of developing T2DM. The Health Professionals Follow-up Study (HPFS) is a prospective cohort study of 51,529 male health professionals between the ages of 40 and 75 years (in 1986 when the study began). In the current study, a substudy of individuals without a history of diabetes, cancer, cardiovascular disease, or pulmonary embolism (n=32,002) were evaluated to determine the relationship between weight training and development of T2DM. The HPFS sends questionnaires to participants every 2 years to assess various factors. Beginning in 1990, eligible persons were asked about the average time spent per week weight training, engaging in other physical activities (swimming, biking, running, walking), and watching TV. Secondary factors included in the questionnaire were self-reported family history, smoking history, height and weight (for body mass index calculation), and diet. If the person reported a new diagnosis of T2DM, a supplementary questionnaire was sent. The subjects were then categorized into four groups based on their responses: 0 minute of weight training or physical activity a week, 1-59 minutes, 60-149 minutes, and >150 minutes.4
The study took place from 1990-2008 (18 years of follow-up) and 2278 participants had confirmed a new diagnosis of T2DM defined by the National Diabetes Data Group criteria from 1990-1996 and the American Diabetes Association criteria from 1998 to 2008. The 14% of men who reported weight training > 150 min per week at baseline generally engaged in more aerobic exercise, watched less TV, ate a healthier diet, and were less likely to smoke than those who reported no weight training. The relative risk for T2DM for men who spend 1-59, 60-149, and > 150 minutes per week weight lifting were 0.88, 0.75 and 0.66, respectively (P <.001) compared to men with no weight training reported. There was a dose-response relationship between increasing amounts of time weight training and a lower risk of developing T2DM. Weight training alone was found to lower the risk of T2DM by 48% (95% CI 1-72%). The association with weight training and risk of T2DM was strongest in men < 65 years of age and without a family history of diabetes. The relative risk of T2DM for those engaging in both aerobic exercise and weight training for > 150 minutes each per week was 0.41 (95% CI, 0.27-0.61).4
The results showed that even minimal weight training alone significantly decreased ...