Residual B-cell function and glycaemic control in diabetic pregnancy.

Serum C-peptide immunoreactivity (CPR), mean blood glucose and blood glycosylated haemoglobin Hb A1c were measured in 23 insulin-dependent diabetic women at 11-12, 23-24, 33-34 and 37-38 gestational weeks in order to elucidate changes in residual B-cell function during pregnancy and their influence on the glycaemic control. CPR values generally increased at the 23-33 gestational weeks, with a significant difference between the mean of the peak values and the mean of the values at the first admission. When the subjects were divided into two groups on the basis of the residual B-cell function at the first admission, the glycaemic control during pregnancy was significantly better in those with higher residual B-cell activity. The overall prevalence of marked residual B-cell activity was higher than previously reported in non-pregnant insulin-dependent diabetic subjects. The results indicate clinically important enhancement in residual B-cell function during pregnancy. The mechanism of this improvement is poorly known although the more strict management of diabetes during gestation may be an important factor.