Phenotypic and metabolic characteristics of women with isolated hyperglycemia in pregnancy-Is the time-point important?

Objective: To examine the phenotypic and metabolic characteristics of pregnant women with one abnormal glucose value (OAV) in the OGTT compared to normals (N) and to gestational diabetes mellitus (GDM) subjects and also to test if the timing of the observed hyperglycemia is related to any difference in their phenotype. Materials and methods: 7618 pregnant women underwent a 100 g OGTT (N = 3813, OAV = 1290, GDM = 2515). The OAV Group was further subdivided according to the time of hyperglycemia: fasting OAV, 1 h OAV and 2-3 h OAV. Demographic data were recorded and indices of insulin sensitivity and secretion were calculated. Results: The OAV Group presented intermediate values in all demographic parameters and in indices of insulin sensitivity and secretion compared to N and GDM Groups (p < 0.01). Regarding the three OAV subgroups: OAV-Fasting was heavier, had increased HOMA-IR and lower HOMA-B index, than the other two. In contrast, the OAV-1 h subgroup had the lower Stumvoll first and second phase indices compared to the others, and also the lowest ISSI (p < 0.01). Conclusion: Isolated hyperglycemia appeared to be heterogeneous. Fasting hyperglycemia was mainly characterized by increased hepatic insulin resistance and impaired basal insulin secretion, while OAV at 1 h presented increased muscle insulin resistance and diminished stimulated insulin secretion. (C) 2010 Elsevier Ireland Ltd. All rights reserved.