Insulin secretion, clearance and sensitivity in black pregnant and non-pregnant women in Harare, Zimbabwe.

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.