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 (HbA(1c)) 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 HbA(1c) values available in medical records over the past 10 years. The correlation between high mean HbA(1c) (>8%) before or after 20 weeks and the incidence of preeclampsia was determined. Mean HbA(1c) values before 20 weeks were further divided into 10- to 15- and 16- to 20-week intervals. Mean values of HbA(1c) in these different gestational periods were analyzed by χ² or Fisher's exact tests. P < 0.05 was considered statistically significant. We found that IDDM pregnant women with high mean values of HbA(1c) (>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 HbA(1c) 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 HbA(1c) value (χ² = 4.49, p = 0.03). We conclude that a significant association between elevated mean HbA(1c) 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.