Fetal doppler and behavioral responses during hypoglycemia induced with the insulin clamp technique in pregnant diabetic women

OBJECTIVE: This study was undertaken to assess human fetal behavior and fetal blood flow after insulin-induced symptomatic maternal hypoglycemia of sufficient magnitude to elicit counterregulatory hormones and a symptomatic response. STUDY DESIGN: Plasma glucose was lowered from approximately 95 mg/dl to 45 mg/dl in decrements of 10 mg/dl every 40 minutes with the insulin clamp technique. In 10 insulin-dependent diabetic women in the third trimester, the fetus was studied by monitoring fetal heart rate and recording fetal body and beathing movements and by performing Doppler waveform analysis with real-time ultrasonography. Maternal levels of glucagon, cortisol, epinephrine, and growth hormone were measured at each plasma glucose level. RESULTS: The mean number of fetal limb and body movements at the start of the study was 25 +- 16 per 15 minutes, which increased to a mean of 38 ± 28 at a glucose level of 60 mg/dl and then declined to a mean of 23 ± 10 at a glucose level of approximately 45 mg/dl. These changes, however, did not achieve statistical significance. In addition, no significant reductions in fetal breathing movements or heart rate were observed, although maternal epinephrine and growth hormone levels were significantly (p < 0.001) increased. No consistent changes in Doppler velocity waveforms were observed. CONCLUSION: These data suggest that fetal well-being remains unaltered in spite of moderate maternal hypoglycemia in diabetic women.