We examined the preventive and therapeutic effects of dietary restriction on diabetes and diabetic nephropathy in OLETF rats. Fifty-five male OLETF rats were randomly divided into five groups as follows: Group A, 30% food restriction from 6 to 80 weeks of age (OLETF: n=14); Group B, 30% food restriction from 6 to 30 weeks of age (OLETF: n=11); Group C, 30% food restriction from 30 to 80 weeks of age (OLETF: n=10), and a full-feeding group (OLETF: n=20).
In group A and B, the development of diabetes was completely prevented until 25 weeks of age, whereas about 30-50% of rats were affected with diabetes after 30 weeks of age in group A and significant increase in the rate of occurrence of diabetes was observed after the start of non-restricted feeding in group B. In group C, the incidence of diabetes gradually decreased after food restriction. Lower levels of urinary protein were observed in the food restriction groups than in the full-feeding OLETF rat group. Histopathologically, both severe fibrosis and atrophy in the pancreatic islets and progression of diabetic nephropathy were prevented by food restriction.
Thus, the results showed that the OLETF rat is useful for the study of dietary control of type II diabetes and its renal complications.