Is exercise training effective in preventing diabetes mellitus in the Otsuka-Long-Evans-Tokushima fatty rat, a model of spontaneous non-insulin-dependent diabetes mellitus?

We determined whether exercise training is effective in preventing the development of diabetes mellitus in a model rat (Otsuka-Long-Evans-Tokushima Fatty [OLETF]) with non-insulin-dependent diabetes mellitus (NIDDM). Thirty male OLETF rats aged 5 weeks were assigned to one of the following three groups: trained rats placed individually in an exercise wheel (EW) cage, EW-control rats housed in the same cages equipped with a fixed rotatory wheel, and sedentary rats maintained two or three to a conventional cage. Eight male diabetes-resistant Long-Evans rats were used as nondiabetic controls. At 24 weeks of age, the trained, EW-control, sedentary, and nondiabetic control rats weighed an average of 445, 559, 621 and 513 g and had abdominal fat deposits of 16, 55, 67, and 23 g, respectively. The mean amount of exercise of trained rats was 5,243 m/d. At 24 weeks of age, the cumulative incidences of diabetes mellitus in sedentary and EW-control rats were 78% and 50%, respectively, while neither trained nor nondiabetic control rats became diabetic. Fasting and 120-minute plasma immunoreactive insulin (IRI) levels after oral glucose administration were significantly lower in the trained group than in the other groups. In vivo insulin-stimulated glucose uptake as measured with a euglycemic clamp was reduced 37% in sedentary rats and increased 35% in trained rats compared with that in nondiabetic control rats. Morphological studies on the pancreas of sedentary and EW-control rats showed enlarged multilobulated fibrotic islets, whereas sections of islets from trained rats appeared normal but slightly enlarged.(ABSTRACT TRUNCATED AT 250 WORDS)