Impaired glucose tolerance in the third trimester of pregnancy: associated factors to its persistence postpartum

Glucose tolerance (75 g OGTT, according WHO) during the third trimester of pregnancy, in 302 women, has formerly been evaluated. Of these, 37 women were reinvestigated, with the same methodology, in absence of pregnancy and lactation, 2 years postpartum. According to oral glucose tolerance three groups were differentiated: group A (n = 14) with normal glucose tolerance (NGT) both in pregnancy and postpartum. Group B1 (n = 12) with impaired glucose tolerance (IGT) in pregnancy but NGT postpartum. Group B2 (n = 11) with IGT both in pregnancy and postpartum. B2 group had increased values (mean + SD) for age (37.0 +/- 6.6 years) versus B1 (30.2 +/- 5.5; p < 0.02) and A (29.5 +/- 5.9); p < 0.02) groups and BMI (32.5 +/- 4.2) versus 26.4 +/- 5.2; p < 0.01 and 23.3 +/- 4.4; p < 0.001 respectively). The ratio between basal insulinogenic indexes (microU IRI/mg BG) during pregnancy and 2 years postpartum has been significantly reduced in B1 (1.4 +/- 0.8) and B2 (1.5 +/- 0.6) as compared to A (2.5 +/- 1.1; p < 0.01) group suggesting, by comparison, the persistence of an increased level of insulin resistance postpartum in B1 and B2 groups. Insulinogenic index, after oral glucose was lower in B2 (34.4 +/- +/- 7.8) versus B1 (53.5 +/- 20.9; p < 0.01) group. These results suggest that, on an increased insulin resistance background, the decrease in glucose induced insulin response and increase in age and BMI are associated to deterioration of glucose tolerance early in the natural history of NIDDM.