Immunoreactive beta-endorphin was measured by radioimmunoassay (RIA) in the pituitary, hypothalamus, pancreas and plasma of female diabetic rats induced by streptozotocin. In addition, pain threshold was determined. The results showed that the concentrations of beta-endorphin in pituitary, hypothalamus, pancreas and plasma began to decrease on the first month after being made diabetic. Then, the levels of beta-endorphin continued to decrease significantly as the course progressed, especially in pancreas and plasma. Diabetic rats consistently showed a decreased pain threshold after 4 weeks. These results suggested that the decrease of beta-endorphin may be related to the course of diabetes and pain threshold.

Red blood cell sorbitol contents were determined with a enzymatic method in 37 diabetics and 19 controls. The fasting blood glucose (FBG) levels and RBC sorbitol contents in the diabetics were significantly higher than that in the controls. RBC sorbitol was positively correlated to FBG, but not to the age of the patients or the type and duration of diabetes mellitus. In 9 patients whose nerve conduction velocity was measured, RBG sorbitol content was negatively correlated with motor nerve conduction velocity of median nerve (r =-0.768, P