Impaired fasting glucose as a marker of heterogeneity of gestational diabetes mellitus. A study of 1025 women living in the region of Kuyavia and Pomerania in Poland.

INTRODUCTION Gestational diabetes mellitus (GDM) is a heterogeneous disease. We hypothesized that fasting hyperglycaemia, defined as impaired fasting glycaemia (IFG), is a marker of metabolic heterogeneity of GDM. The aim of this study was to compare selected metabolic parameters in two groups of women with GDM, one with normal fasting glycaemia (NFG GDM) and another with IFG, to test this hypothesis. MATERIAL AND METHODS Metabolic parameters of 1025 women with GDM (mean age 29 years): glucose and insulin at 0 OGTT, glucose at 2-h oral glucose tolerance test (OGTT), body mass index before pregnancy, parity, and gestational age at diagnosis of GDM were analyzed. Insulin resistance and beta-cell function were evaluated by HOMA indexes (HOMA-IR and HOMA-B) at the diagnosis of GDM. RESULTS The IFG GDM group (23%) consisted of isolated IFG (30%), IFG/IGT (60%), and IFG/DM (10%). The NFG GDM group (77%) consisted of isolated IGT (98%) and NFG/DM (2%). Women with IFG GDM were characterized by higher prepregnancy BMI, earlier diagnosis of GDM, higher HOMA-IR (p < 0.03), and lower HOMA-B (p < 0.01) compared to NFG GDM. In the IFGGDM group, DM was characterized by lower HOMA-B compared with isolated IFG and IFG/IGT. In the NFG GDM group, isolated IGT and DM were characterized by similar HOMA-IR and HOMA-B. CONCLUSIONS Impaired fasting glucose distinguishes more severe metabolic phenotypes of GDM compared toGDM with normal fasting glucose concentrations.