From the Guidelines
The primary hormonal cause of gestational diabetes mellitus (GDM) in a pregnant woman is human placental lactogen (hPL), which is the main contributor to insulin resistance during pregnancy. Gestational diabetes mellitus (GDM) develops during pregnancy primarily due to insulin resistance caused by placental hormones, with human placental lactogen (HPL) being the main contributor 1. HPL, produced by the placenta in increasing amounts throughout pregnancy, antagonizes insulin action in maternal tissues, causing insulin resistance. This physiological adaptation ensures adequate glucose supply to the developing fetus but can lead to GDM when the maternal pancreas cannot produce enough insulin to overcome this resistance.
Key Points
- The patient's elevated glucose level after the glucose challenge test indicates impaired glucose tolerance, consistent with GDM.
- While other hormones like progesterone and cortisol contribute to insulin resistance during pregnancy, HPL has the most significant effect.
- The other options - estradiol, oxytocin, prolactin, and thyroxine-binding globulin - do not play primary roles in causing the insulin resistance that leads to gestational diabetes.
Hormonal Effects
- HPL is the primary hormone responsible for insulin resistance in pregnancy, leading to GDM.
- Other hormones, such as progesterone and cortisol, also contribute to insulin resistance but to a lesser extent.
- The effects of HPL on insulin resistance are well-documented in the literature, with studies showing a strong correlation between HPL levels and insulin resistance in pregnant women 1.
From the Research
Primary Hormonal Cause of Gestational Diabetes Mellitus (GDM)
The primary hormonal cause of GDM is related to the effects of human placental lactogen (hPL) 2, 3.
Effects of Human Placental Lactogen (hPL)
- hPL induces lipolysis, increasing circulating free fatty acids which activate protein kinase C, inhibiting insulin signaling 2.
- The anti-insulin effect of hPL raises maternal blood glucose levels, allowing the fetus to use glucose as a nutrient 3.
Other Hormonal Effects
- Other hormones such as progesterone, estrogen, prolactin, and cortisol may also influence beta-cell function and/or peripheral tissue sensitivity to insulin, but their roles in human pregnancy are not fully understood 4.
- Estradiol, oxytocin, prolactin, and thyroxine-binding globulin are not directly identified as primary causes of GDM in the provided studies.