Abstract

Diabetes in pregnancy is known to be associated with increased occurrence of both fetal and maternal adverse events. Glucose and HbA1C are established tools in the assessment of glycemic control. Although HbA1C reference intervals are well established for the general population, reference intervals for pregnant women are not clearly defined. Objectives: To determine the reference value of fasting blood glucose and HbA1C in normal pregnant Nigerian women. Methods: Fasting blood glucose and HbA1C levels were measured in 268 normal pregnant women of which 47 were in the 1st trimester (<14 weeks), 97 in the 2nd (14-27 weeks) and 124 in the 3rd trimester (28-39 weeks) of pregnancy. 20 healthy non pregnant women matched for age, parity and without family history of diabetes were also randomly recruited into the study as control. Fasting blood glucose was determined by the glucose oxidase method while HbA1C was determined by ion exchange resin method (Quimica Clinica Aplicada S.A., Amposta/Espana). Average values are presented as Mean + SEM while relationships between values were determined using Pearson’s correlation analysis. Significance of P values of determinations is set at P < 0.05. Results: Fasting blood glucose levels of pregnant women in all trimesters were lower compared to the non pregnant women. HbA1C values in the pregnant women were lower compared to non-pregnant women; values in the 2nd and 3rd trimester were lower than those in the 1st trimester of pregnancy. Conclusion: HbA1C levels are lower in normal pregnancy and further decreased as pregnancy advances. A decrease of the upper normal limit of HbA1C from 7.8% before pregnancy to 5.6% in the third trimester of pregnancy is of significant clinical importance when defining the reference range for HbA1C during pregnancy in women with diabetes.