Glycosylated hemoglobin in insulin-dependent diabetes mellitus related to preeclampsia.

Preeclampsia may occur due to failure of the second wave of trophoblastic invasion between 16 to 20 weeks of gestation. We studied whether the mean value of glycosylated hemoglobin (HbA1c) during this gestational period was associated with an increased incidence of preeclampsia in insulin-dependent diabetes mellitus. We conducted a retrospective study of 131 insulin-dependent diabetes mellitus (IDDM) pregnancies with HbA1c values available in medical records over the past 10 years. The correlation between high mean HbA1c (>8%) before or after 20 weeks and the incidence of preeclampsia was determined. Mean HbA1c values before 20 weeks were further divided into 10- to 15- and 16- to 20-week intervals. Mean values of HbA1c in these different gestational periods were analyzed by chi(2) or Fisher's exact tests. P < 0.05 was considered statistically significant. We found that IDDM pregnant women with high mean values of HbA1c (>8%) had a significantly higher rate of preeclampsia than those with normal mean values (45 vs. 24%, p = 0.018). However, we found that IDDM pregnant women with an elevated mean HbA1c value at 16-20 weeks', but not 10-15 weeks' or after 20 weeks', gestation had a significantly higher incidence of preeclampsia than those with normal mean HbA1c value (chi(2) = 4.49, p = 0.03). We conclude that a significant association between elevated mean HbA1c values at 16-20 weeks' gestation and a high frequency of preeclampsia in IDDM pregnancies suggests that glycosylated hemoglobin may play an important role in the pathogenesis of preeclampsia in IDDM pregnant women.