Vitamin C (vitC) is essential for normal pregnancy and fetal development and poor vitC status has been related to complications of pregnancy. We have previously shown lower vitC status in diabetic women throughout pregnancy compared to that of non-diabetic controls. Here, we evaluate the relationship between vitC status late in diabetic pregnancy in relation to fetal outcome, complications of pregnancy, diabetic characteristics, and glycemic control based on data of 47 women from the same cohort. We found a significant relationship between the maternal vitC level > or ≤ the 50% percentile of 26.6 µmol/L, respectively, and the umbilical cord blood vitC level (mean (SD)): 101.0 µmol/L (16.6) versus 78.5 µmol/L (27.8), p = 0.02; n = 12/16), while no relation to birth weight or Apgar score was observed. Diabetic women with complications of pregnancy had significantly lower vitC levels compared to the women without complications (mean (SD): 24.2 µmol/L (10.6) vs. 34.6 µmol/L (14.4), p = 0.01; n = 19 and 28, respectively) and the subgroup of women (about 28%) characterized by hypovitaminosis C (<23 µmol/L) had an increased relative risk of complications of pregnancy that was 2.4 fold higher than the one found in the group of women with a vitC status above this level (p = 0.02, 95% confidence interval 1.2–4.4). No correlation between diabetic characteristics of the pregnant women and vitC status was observed, while a negative association of maternal vitC with HbA1c at delivery was found at regression analysis (r = −0.39, p < 0.01, n = 46). In conclusion, our results may suggest that hypovitaminosis C in diabetic women is associated with increased risk of complications of pregnancy.