Insulin-anti-insulin complexes in diabetic women and their neonates.

It is known that insulin does not cross placenta, whereas maternal anti-insulin antibodies do. We have therefore investigated insulin antibodies and insulin-anti-insulin complexes both in pregnant diabetic women during pregnancy and in umbilical cord blood from their new-born infants. Forty-seven diabetic pregnant women and 23 new-born-infants of these diabetic women were studied. All the pregnant patients were studied at the end of pregnancy and in 27, at least on one other occasion during pregnancy. All the patients were treated with insulin during pregnancy: 26 had Type 1 (insulin-dependent) diabetes, 14 Type 2 (non-insulin-dependent) diabetes and seven had gestational diabetes. Insulin antibodies were found in 62% of the Type 1 diabetic patients, in 71% of the Type 2 diabetic patients and in 43% of the gestational diabetic patients. There were present in 48% of the infants studied. Insulin-anti-insulin complexes were found in 37% of the women with Type 1 diabetes, in 21% of those with Type 2 diabetes and in 14% of those with gestational diabetes. Complexes were found in 38% of the new-born infants. The presence of these complexes in the babies was more strongly correlated with their occurrence in their mothers at the beginning than at the end of pregnancy. Insulin-anti-insulin complexes are thus present in the neonatal circulation. They may differ from those in their mothers and they may have pathophysiological and clinical importance.