[en] Earlier reports from their laboratory showed the induction of the insulin-deficient diabetic state in adult rats was associated with an accumulation of zinc, copper, and a metallothionein-like zinc and copper binding protein in the soluble fraction of liver and kidney. Based upon chromatographic and electrophoretic properties, -SH to metal ratio and amino acid composition, they now report that elevated concentrations of metallothioneins (MT)-I and -II are indeed present in diabetic rat liver and kidney cytosol. The relative rates of MT synthesis in tissues from diabetic and control rats were measured by comparing incorporation of ³⁵S-cysteine into MT vs. total cytoplasmic proteins at 5 h after injection of the precursor. The relative rates of MT synthesis in livers from rats diabetic for 10 d and fed either chow or purified diet containing 13 or 35 ppm copper were 1.4, 2.3 and 2.8 times greater, respectively, than control rats fed the same diets. Higher relative rates of MT synthesis were also observed in kidneys from diabetic rats fed purified diets compared to controls. Maximal relative rates of MT synthesis in diabetic liver and kidney were observed at 4 and 10 d, respectively, after onset of diabetes. The half-lives of cytoplasmic MT in liver and kidney from diabetic (10 d) rats were 1.3 and 2.6 days, respectively; half-lives of MT in control liver and kidney were 5.0 and 2.1 days, respectively