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Early reexamination of carbohydrate metabolism via an oral glucose tolerance test (OGTT) is recommended after pregnancy with gestational diabetes (GDM). In this report, we aimed to assess the dominant patterns of dynamic OGTT measurements and subsequently explain them by meanings of the underlying pathophysiological processes. Principal components analysis (PCA), a statistical procedure that aims to reduce the dimensionality of multiple interrelated measures to a set of linearly uncorrelated variables (the principal components) was performed on OGTT data of glucose, insulin and C-peptide in addition to age and body mass index (BMI) of 151 women (n = 110 females after GDM and n = 41 controls) at 3-6 mo after delivery. These components were explained by frequently sampled intravenous glucose tolerance test (FSIGT) parameters. Moreover, their relation with the later development of overt diabetes was studied. Three principal components (PC) were identified, which explained 71.5% of the variation of the original 17 variables. PC1 (explained 47.1%) was closely related to postprandial OGTT levels and FSIGT-derived insulin sensitivity (r = 0.68), indicating that it mirrors insulin sensitivity in the skeletal muscle. PC2 (explained 17.3%) and PC3 (explained 7.1%) were shown to be associated with β-cell failure and fasting (i.e., hepatic) insulin resistance, respectively. All three components were related with diabetes progression (occurred in n = 25 females after GDM) and showed significant changes in long-term trajectories. A high amount of the postpartum OGTT data is explained by principal components, representing pathophysiological mechanisms on the pathway of impaired carbohydrate metabolism. Our results improve our understanding of the underlying biological processes to provide an accurate postgestational risk stratification., (Copyright © 2015 the American Physiological Society.)

Risk stratification after pregnancy with gestational diabetes mellitus (GDM) is based on screening with the 2-h oral glucose tolerance test (OGTT). Actually, prediabetes and diabetes are diagnosed by impaired fasting [fasting plasma glucose (FPG)] and 120 min-postload glucose levels (120'-PLG). We hypothesized that the clinical information could be improved by including measurements at different time points from the OGTT in the medical decision-making process. One hundred ten women with previous gestational diabetes (pGDM) and 41 controls were included 3-6 mo after delivery and underwent specific metabolic assessments: 3-h OGTT, frequently sampled intravenous glucose tolerance test (FSIGT) with markers of inflammation and endothelial function. pGDMs were annually invited for reexaminations for a maximum of 10 yr. Multiple linear regression suggested that postload glucose levels at 60 min (60'-PLG) were a better predictor for insulin sensitivity [β: -0.10, 95% confidence interval (CI) -0.14 to -0.05, P < 0.001] and disposition index (DI) (β: -0.07, 95% CI -0.12 to -0.02, P = 0.004) estimated from the FSIGT compared with other time points during the OGTT. The association between 60'-PLG and insulin secretion was of particular importance in women after GDM. We further identified associations of 60'-PLG with ultrasensitive C-reactive protein, plasminogen activator inhibitor 1, tissue plasminogen activator, endothelial-leukocyte adhesion molecule 1, and intercellular adhesion molecule (ICAM)-1. There appeared to be no interactions between females with pGDM and controls, suggesting comparable effects. We observed that 60'-PLG levels were closely related to the later onset of diabetes independent from the routinely measured FPG and 120'-PLG levels. Our data suggest that the sole interpretation of FPG and 120'-PLG of the OGTT leads to significant loss of information. Particularly 60'-PLG was shown to distinguish women at low or high metabolic and cardiovascular risk.