Numerous experimental studies have implied a link between diabetes-induced 
abnormal lipid buildup in the myocardium and the development of cardiomyopathy. 
Because the diabetic state in rats is associated with lowered T3 
(triiodothyronine) and T4 levels and because diabetic patients excrete large 
amounts of myo-inositol, a lipotropic agent, we investigated the effects of 
myo-inositol and T3 on the elevated myocardial lipid levels and depressed 
cardiac performance of streptozocin (55 mg/kg i.v.)-induced diabetic (STZ-D) 
rats. myo-inositol (2.5 g.kg-1.day-1 in the drinking water) and T3 (30 
micrograms.kg-1.day-1 s.c.) were given for an 8-wk period 3 days after diabetes 
induction. Untreated diabetic rats were characterized by a decreased rate of 
body weight gain, hyperglycemia, and hypoinsulinemia, which were not altered 
after myo-inositol and/or T3 treatment. Thyroid status of diabetic animals was 
normalized by T3 alone or in combination with myo-inositol but not by 
myo-inositol alone. The elevations in plasma and myocardial lipids associated 
with the diabetic state were prevented by myo-inositol treatment. However, the 
plasma lipid and myocardial cholesterol levels in diabetic rats remained 
elevated or were further increased with treatment with T3 or myo-inositol plus 
T3. myo-inositol treatment partially improved cardiac performance in STZ-D rats. 
T3 treatment alone did not prevent cardiac dysfunction in diabetic rats. There 
was, however, some improvement in heart function in the groups treated with both 
myo-inositol and T3, coinciding with a significant decrease in the myocardial 
triacylglycerol level. The data indicate that a possible correlation may exist 
between elevated myocardial triacylglycerol levels and cardiac dysfunction in 
diabetic rats.