Abnormal dietary regulation of erythrocyte insulin receptor affinity in non-insulin-dependent diabetes mellitus.
Decreased insulin binding to receptors is associated with the insulin resistance of obese and non-obese non-insulin-dependent diabetics. 'Down Regulation' by elevated insulin levels has been suggested as the cause, but factors influencing receptor affinity have not been examined. To investigate the control of receptors in diabetes, 10 non-insulin-dependent diabetics and 10 normal subjects were studied after 6 d on low and 6 d on high calorie diets of fixed composition (700 and 2800 Kcal/70 kg of ideal body weight). The binding of insulin by erythrocytes of non-diabetics, as predicted, increased on the low and decreased on the high calorie diets, due to altered affinity. In contrast, the binding in the diabetics did not change significantly, and the responses to the low and high calorie diets were less than in the normal subjects (P less than 0.05 and P less than 0.001 respectively). Indeed, the insulin binding in all 5 non-obese diabetics changed in the opposite direction (P less than 0.01) to the non-diabetics, whereas the obese diabetics showed a mixed response. The changes in receptor binding in the diabetics was completely unrelated to the diurnal plasma insulin levels during 24 h studies. We conclude that the dietary regulation of erythrocyte insulin receptor affinity in non-insulin-dependent diabetes is abnormal, and insulin receptor affinity is regulated by factors other than insulin. The relation of this abnormality to the insulin resistance needs further investigation.
D000368:Aged; D001835:Body Weight; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000378:metabolism*; D004032:Diet; D002149:Energy Intake; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism*; D011972:Receptor, Insulin / Q000378:metabolism*
D007328:Insulin; D011972:Receptor, Insulin