Abstract

Objective: HbA_1C levels have been shown to be elevated in relation to glycemia in late pregnancy, although the precise mechanisms remain undetermined. We hypothesized that iron deficiency is involved in HbA_1C increase in late pregnancy.

Methods: In Study 1, HbA_1C, serum glycated albumin (GA), erythrocyte indices and iron metabolism indices were determined in 47 non-diabetic pregnant women not supplemented with iron divided into 4 groups according to gestational period (Group I, 21-24 weeks, Group II, 25-28 weeks; Group III, 29-32 weeks; Group IV, 33-36 weeks). In Study 2, these determinants were obtained at two gestational periods (20-23 weeks and 32-33 weeks) in 17 non-diabetic pregnant women.

Results: In Study 1, HbA_1C levels were higher in Groups III and IV than those Groups I and II, while serum GA levels were not different between these four groups. Hemoglobin, mean corpuscular hemoglobin (MCH), serum transferrin saturation and serum ferritin were lower in Groups III and IV. HbA_1C levels were negatively correlated with MCH, serum transferrin saturation and serum ferritin. In Study 2, HbA_1C levels were significantly increased at gestational week 32-33 from those at week 20-23, while serum GA levels did not differ between the two gestational periods. MCH, serum transferrin saturation and serum ferritin were decreased at gestational week 32-33. HbA_1C levels showed a negative correlation with MCH, serum transferrin saturation and serum ferritin.

Conclusions: HbA_1C levels were elevated in late pregnancy due to iron deficiency. Serum GA may offer a better index for monitoring glycemic control in pregnancy.