The effects of physical training in people with insulin-dependent diabetes

American College of Sports Medicine position stand. Exercise and type 2 diabetes

Physical activity, including appropriate endurance and resistance training, is a major therapeutic modality for type 2 diabetes. Unfortunately, too often physical activity is an underutilized therapy. Favorable changes in glucose tolerance and insulin sensitivity usually deteriorate within 72 h of the last exercise session: consequently, regular physical activity is imperative to sustain glucose-lowering effects and improved insulin sensitivity. Individuals with type 2 diabetes should strive to achieve a minimum cumulative total of 1,000 kcal x wk(-1) from physical activities. Those with type 2 diabetes generally have a lower level of fitness (VO2max) than nondiabetic individuals. and therefore exercise intensity should be at a comfortable level (RPE 10-12) in the initial periods of training and should progress cautiously as tolerance for activity improves. Resistance training has the potential to improve muscle strength and endurance, enhance flexibility and body composition, decrease risk factors for cardiovascular disease, and result in improved glucose tolerance and insulin sensitivity. Modifications to exercise type and/or intensity may be necessary for those who have complications of diabetes. Individuals with type 2 diabetes may develop autonomic neuropathy, which affects the heart rate response to exercise, and as a result, ratings of perceived exertion rather than heart rate may need to be used for moderating intensity of physical activity. Although walking may be the most convenient low-impact mode, some persons, because of peripheral neuropathy and/or foot problems, may need to do non-weight-bearing activities. Outcome expectations may contribute significantly to motivation to begin and maintain an exercise program. Interventions designed to encourage adoption of an exercise regimen must be responsive to the individual's current stage of readiness and focus efforts on moving the individual through the various "stages of change."

Clenbuterol-induced insulin resistance in calves measured by hyperinsulinemic, euglycemic clamp technique

Hyperinsulinemic, euglycemic clamp tests were performed on calves before and after clenbuterol treatment. Clenbuterol was given as 2 intramuscular injections with an interval of about 12 h. The dose used was 1 microgram/kg b.w. The treatment resulted in increased plasma levels of insulin and glucose. The results of the clamp tests showed that clenbuterol induced a transient decrease in insulin sensitivity. Both insulin mediated glucose disposal (M), expressed as mumol/kg live b.w./min. and the M/I-index (M divided by the average insulin concentration at steady state) were significantly reduced after treatment. The effect of clenbuterol on carbohydrate metabolism seemed to be rather short-lived, since significant changes occurred only in animals treated 5-6 h prior to the test. According to the literature, the metabolic effects of clenbuterol have been studied only after the high doses used for growth promoting purposes. The results from the present study showed that similar changes occur also after doses at the therapeutic level. The hyperinsulinemic, euglycemic clamp test was considered to be a valuable tool for the study of insulin sensitivity in cattle.