AIM:The ultrastructure,the levels of NO - 2/NO - 3 were investigated in the myocardium of rats with non-insulin dependent diabetes mellitus. METHODS: In order to establish a model of non-insulin dependent diabetes mellitus (NIDDM), we injected rats with small dose streptozocoi (iv). Two weeks after the injection, the rats developed impaired glucose tolerance. Then, they were fed with high energy diet for eight weeks to form NIDDM. RESULTS: (1) The ultrastructures of cardiac myocytes of NIDDM rats were changed evidently, with swelled mitochondrion and widened intercalated-disk gap; (2) The levels of NO - 2/NO - 3 in the heart tissue of NIDDM rats were significantly lower than those of normal rats( P