Insulin Secretory Patterns and Uteroplacental Doppler Flow Velocimetry in Pregnancies Complicated by Carbohydrate Intolerance: Is There any Relationship?

Objective: To evaluate the relationship between insulin levels and uter-oplacental vascular resistance in third-trimester pregnancies complicated by impaired carbohydrate tolerance. Methods: Fifty-two patients were admitted to the study. After a 3–h oral glucose tolerance test (OGTT), a color Doppler evaluation of uterine and umbilical arteries was performed. Results: According to O'Sullivan criteria, 14 patients had impaired gestational glucose tolerance (IGGT), 18 patients had gestational diabetes (GDM), and 20 subjects had normal glucose tolerance and served as controls. On the basis of the insulinemic response to OGTT, the patients were then classified as normoinsulinemic or hyperinsulinemic, with a cutoff value for the area under the curve of 240,360 pmol/L × 180 min. Hyperinsulinemic patients showed greater values of the “highest” uterine artery resistance index (RI) when compared to controls (P < 0.01); the “lowest” uterine artery RI was slightly, but not significantly, increased. Moreover, a significant linear correlation was found between insulin response to OGTT and “highest” uterine artery RI (P < 0.034, r = 0.29), as well as between insulin and diastolic blood pressure (DBP) (P < 0.001, r = 0.47); DBP was also significantly related to the “highest” uterine artery RI (P < 0.033, r = 0.29). By contrast, no differences were found in the three groups with respect to umbilical artery pulsatility index (PI) and pregnancy outcome. Conclusions: From our preliminary study, we conclude that a relationship exists between insulin secretory patterns and uterine vascular indices in pregnancies complicated by carbohydrate intolerance, but the cause of this relationship is yet to be clarified; we cannot exclude a possible involvement of arterial blood pressure