Abstract

Objective To define the metabolic phenotype of pregnant women with one abnormal value during OGTT (OAV) and to test if OAV could be considered metabolically comparable to Gestational Diabetes (GDM) or a specific entity between GDM and normal pregnancy.

Research design and Methods After 100 g 3-h OGTT, 4053 pregnant women were classified as: GDM, OAV or NGT. OAV were subdivided in: fasting hyperglycaemia (F-OAV), 1-hr hyperglycaemia (1h-OAV), 2 or 3-hr hyperglycemia (L-OAV). Derived from OGTT, we measured insulin sensitivity (ISI Matsuda) and insulin secretion (Homa-B, first and second phase insulin secretion). The product of first-phase index and ISI was calculated to obtain the Insulin secretion--sensitivity index (ISSI).

Results GDM was diagnosed in 17.9 %, OAV in 18.7 %; GDM and OAV women were older, had higher BMI and serum triglyceride levels than NGT (all p<0.05). NGT women had the highest ISI followed by OAV (-21.7%) and GDM (-32.1 %). HOMA-B resulted comparable between OAV and GDM but significantly (p<0.01) lower than NGT; first and second phase insulin secretion appeared progressively reduced from NGT to OAV and GDM (p<0.01). ISSI was higher in NGT as compared to both OAV (-34%) and GDM women (-51.7%) (p<0.001). Among OAV subgroups 1h-OAV showed the lowest ISSI (p<0.05).

Conclusions OAV and GDM women are clinically undistinguishable and both groups are different from NGT. GDM and OAV showed impaired insulin secretion and insulin sensitivity, although these defects are more pronounced in GDM. 1 h-OAV could be considered a more severe condition compared to other OAV subgroups.