GLYCEMIC THRESHOLDS FOR SPONTANEOUS-ABORTION AND CONGENITAL-MALFORMATIONS IN INSULIN-DEPENDENT DIABETES-MELLITUS

Objective: To test the hypothesis that women with insulin-dependent (t ype I) diabetes have a threshold of glycemic control in early pregnanc y for increased risks of spontaneous abortion and congenital malformat ions. Methods: Receiver-operating characteristic (ROC) curves were for med for the occurrence of abortion and malformations as a function of the median first-trimester preprandial blood glucose concentration and the first measured glycohemoglobin concentration in pregnant women wi th type I diabetes. Results: Fifty-two of the 215 women (24%) who enro lled before 9 weeks' gestation had spontaneous abortions. Six percent of the women enrolled before 14 weeks had infants with major congenita l malformations. Thresholds for an increased risk of abortion and malf ormations were a median first-trimester blood glucose concentration of 120-130 mg/dL or an initial glycohemoglobin concentration of 12-13% ( 6.2-7.5 standard deviations above the normal mean). Conclusions: Type I diabetic women with initial glycohemoglobin concentrations in pregna ncy above 12% or median first-trimester preprandial glucose concentrat ions above 120 mg/dL have an increased risk of abortion and malformati ons. Below these glycemic thresholds, the risks are comparable to thos e in nondiabetic women.