High prevalence of early (1st trimester) gestational diabetes mellitus in Polish women is accompanied by marked insulin resistance - comparison to PCOS model.

Introduction: Both pregnancy and polycystic ovary syndrome (PCOS) constitute insulin-resistant states that are associated with an increased prevalence of glucose intolerance. Some women demonstrate significant insulin resistance (IR) and develop gestational diabetes (GDM) even in the 1st trimester. We compared surrogate IR indices in 1st-trimester pregnant women and in women with PCOS (Rotterdam consensus criteria).
Material and Methods: We performed a 75-g oral glucose tolerance test (OGTT) with insulin measurements in 106 healthy 1st-trimester pregnant women at 9.9 ± 2.6 weeks of gestation and in 418 women with PCOS. We assessed IR (HOMA-IR, QUICKI, Matsuda, Belfiore, and Stumvoll indices) as well as the prevalence of GDM according to the International Association of Diabetes and Pregnancy Study Groups (IADSPG) and World Health Organization (WHO) (1999) criteria.
Results: Despite having a slightly lower BMI (p = 0.027), pregnant women had either similar (QUICKI, Belfiore index, Stumvoll0-120 min) or greater IR than women with PCOS (e.g. HOMA-IR 3.85 ± 6.11 vs. 2.64 ± 2.04, p = 0.002), while only the Matsuda index demonstrated less IR in pregnant women (p = 0.003). The correlation between IR indices in pregnant women showed marked variability, ranging from r = 0.334 (HOMA-IR vs. Belfiore index) to r = -1.0 (HOMA-IR vs. QUICKI, p < 0.001). This was accompanied by a high prevalence of GDM (14.2% and 9.4%, IADPSG and WHO criteria, respectively). Women with GDM diagnosed according to IADPSG criteria demonstrated greater IR than pregnant women without GDM. In women with GDM diagnosed according to WHO (1999) criteria these differences were visible only for OGTT-derived IR indices (Belfiore, Matsuda, and Stumvoll0-120 index).
Conclusions: Depending on the choice of IR indices, healthy 1st-trimester pregnant women demonstrate either similar or greater IR than women with PCOS, and this is accompanied by a high prevalence of early GDM. It remains to be established whether GDM screening should be performed in the 1st trimester.