Dataset Information

Isolated hyperglycemia at 1 hour on oral glucose tolerance test in pregnancy resembles gestational diabetes mellitus in predicting postpartum metabolic dysfunction.

ABSTRACT:

Objective

Gestational impaired glucose tolerance (GIGT), defined by a single abnormal value on antepartum 3-h oral glucose tolerance test (OGTT), is a metabolically heterogeneous disorder. Indeed, the antepartum metabolic phenotype of women with a single abnormal value at 1 h during the OGTT (1-h GIGT) resembles that of women with gestational diabetes mellitus (GDM), whereas GIGT at 2 or 3 h (2/3-h GIGT) is similar to normal glucose tolerance (NGT). Thus, we hypothesized that 1-h GIGT would be associated with the same adverse outcomes as GDM, i.e., increased infant birth weight and postpartum metabolic dysfunction.

Research design and methods

A total of 361 women underwent an antepartum glucose challenge test (GCT) and a 3-h OGTT, assessment of obstetrical outcome at delivery, and metabolic characterization by OGTT at 3 months postpartum. The antepartum GCT/OGTT identified five study groups: GDM (n = 97), 1-h GIGT (n = 28), 2/3-h GIGT (n = 34), abnormal GCT NGT (abnormal GCT with NGT on OGTT) (n = 128), and normal GCT NGT (normal GCT with NGT on OGTT) (n = 74).

Results

Caesarian section rate was higher in women with 1-h GIGT, but birth weight did not differ significantly between the non-GDM groups (P = 0.1978). At 3 months postpartum, glycemia (area under the glucose curve) progressively increased across the groups from normal GCT NGT to abnormal GCT NGT to 2/3-h GIGT to 1-h GIGT to GDM (P < 0.0001), while both insulin sensitivity (IS(OGTT)) and beta-cell function (insulinogenic index/homeostasis model assessment of insulin resistance [HOMA-IR]) progressively decreased (P = 0.002 and P < 0.0001, respectively). The strongest independent negative predictors of insulinogenic index/HOMA-IR were GDM (t = -4.1, P < 0.0001) and 1-h GIGT (t = -3.8, P = 0.0002).

Conclusions

Like GDM, 1-h GIGT is associated with postpartum glycemia, insulin resistance, and beta-cell dysfunction.

PROVIDER: S-EPMC2453676 | BioStudies |

REPOSITORIES: biostudies

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Project description:<h4>Background</h4> Recent studies have suggested that gestational diabetes (GDM) is a heterogeneous condition with distinct subtypes determined by whether the predominant metabolic abnormality is impaired insulin sensitivity or deficient insulin secretion. However, it is not known if the elevated future risk of pre-diabetes/diabetes associated with GDM varies according to these subtypes. Thus, we sought to evaluate maternal metabolic function in the 1st year postpartum in relation to GDM subtypes. <h4>Methods</h4> In this prospective cohort study conducted in Toronto, Canada, 613 women underwent GDM screening by oral glucose tolerance test (OGTT) in pregnancy, followed by repeat OGTT at both 3-months and 12-months postpartum between 09/2003 and 03/2016. The antepartum OGTT identified 3 groups of women: GDM with predominant sensitivity defect (GDM-sensitivity), GDM with predominant secretion defect (GDM-secretion), and non-GDM. <h4>Findings</h4> Antepartum findings persisted after pregnancy, with lower insulin sensitivity in GDM-sensitivity (Matsuda index; HOMA-IR) and lower insulin secretion in GDM-secretion (Stumvoll first-phase; insulinogenic index (IGI)) at both 3-months and 12-months (all p<0.005). Beta-cell compensation (Insulin Secretion-Sensitivity Index-2; IGI/HOMA-IR) was lower in both GDM subtypes compared to non-GDM (all p<0.0005) but did not differ between GDM-sensitivity and GDM-secretion. Similarly, both subtypes exhibited higher post-challenge glycemia on OGTT at 3-months and 12-months than non-GDM (all p<0.0005) but did not differ from one another. The prevalence of pre-diabetes/diabetes was higher in both GDM-sensitivity (30.9%; 95%CI: 21.7–41.2) and GDM-secretion (27.6%; 16.7–40.9) than in non-GDM (10.4%; 7.7–13.6) at 12-months (both p<0.005), with no difference between GDM subtypes (p = 0.75). <h4>Interpretation</h4> Beta-cell dysfunction, glycemia and incident pre-diabetes/diabetes do not vary between GDM subtypes in the 1st year postpartum. <h4>Funding</h4> Canadian Institutes of Health Research; Diabetes Canada