Insulin action in women with polycystic ovary syndrome and its relation to gestational diabetes

STUDY QUESTION: How does insulin action change during pregnancy in women with polycystic ovary syndrome (PCOS) who develop gestational diabetes (GDM) compared with women with PCOS who do not?

SUMMARY ANSWER: Women with PCOS who develop GDM already show disturbed insulin action early in pregnancy.

WHAT IS KNOWN ALREADY: Pregnant women with PCOS are at increased risk of developing GDM compared with women without PCOS.

STUDY DESIGN, SIZE, DURATION: This study represents a post hoc analysis of a subgroup of pregnant women with PCOS participating in a multicentre prospective cohort study. A total of 72 women were included.

PARTICIPANTS/MATERIALS, SETTING, METHODS: Women with PCOS and a wish to conceive were included before conception and followed during pregnancy. Insulin, glucose, homeostasis model assessment of insulin resistance (HOMA-IR), sex hormone-binding globulin (SHBG) and testosterone were analysed at three different time points in women who developed GDM and women who did not.

MAIN RESULTS AND THE ROLE OF CHANCE: Seventy-two pregnant women with PCOS were included of which 22 (31%) women developed GDM. Both insulin levels and HOMA-IR were significantly higher at each sampling point in women with PCOS who developed GDM. SHBG levels were significantly lower before conception and in the second trimester compared with women who did not develop GDM. Testosterone concentrations were significantly lower before conception in women who developed GDM. After adjusting for BMI, waist circumference and waist/hip ratio, the differences in insulin, HOMA-IR, SHBG and testosterone levels remained largely the same.

LIMITATIONS, REASONS FOR CAUTION: Selection bias cannot be excluded since only women from one centre with a complete blood sampling set were included in this study.

WIDER IMPLICATIONS OF THE FINDINGS: The knowledge that women with PCOS who develop GDM already have a disturbed insulin action early in pregnancy is likely to be useful in considering the pathophysiology processes underlying this disorder in this specific group of women.