Objective: To assess whether reported gestational differences in glucose tolerance in Caucasian and Black women could be due to alterations in insulin secretion, clearance or sensitivity.
Design: Cross sectional survey.
Setting: Antenatal Clinic, Harare; Department of Medical Laboratory Sciences, University of Zimbabwe.
Subjects: 90 healthy women in all the trimesters of pregnancy and 30 healthy non-pregnant women of reproductive age.
Main outcome measures: Fasting (basal) plasma insulin, C-peptide and glucose concentration. Fasting plasma C-peptide, C-peptide to insulin ratio and glucose to insulin ratio were used as indices of insulin secretion, hepatic insulin clearance and insulin sensitivity respectively.
Results: Not all means of the fasting plasma glucose levels amongst the four groups of women were equal (p < 0.001), with all possible comparisons being significant except for the first and second trimester groups. Among the comparisons of the means of the glucose:insulin ratio in the four groups of women, only the means of the first and second trimester women differed (mean difference = 0.23, honestly significance difference = 0.20). All groups were comparable in the means of plasma insulin, C-peptide levels and the C-peptide:insulin ratio.
Conclusion: Since fasting plasma insulin, C-peptide and C-peptide:insulin ratio were not significantly altered in all trimesters of pregnancy, these data suggest normal basal insulin secretion and clearance during gestation in these sub-Saharan African women.