Endocrine and Metabolic Disorders Impacting Pregnancy

Gestational diabetes, also known as gestational diabetes mellitus, or GDM for short, is glucose intolerance that occurs during pregnancy, whereas pregestational diabetes is diabetes that is present prior to pregnancy.

Alright, so, hormones produced during pregnancy cause changes in maternal glucose metabolism to support the pregnancy and to allow the fetus to receive a steady supply of glucose necessary for fetal growth and development.

The early part of pregnancy can be described as an anabolic state, which increases fat stores, augments blood supply, and supports the growth of the fetus and maternal tissue like uterus, placenta, and breast tissue. During this time, insulin secretion increases, along with glucose utilization and storage in adipose and muscle cells.  

Later, as the pregnancy progresses, it begins to exert a diabetogenic effect on glucose metabolism, which means that there’s increasing maternal insulin resistance and decreased utilization of glucose. This results in higher levels of maternal blood glucose and increased transfer of glucose to the fetus. During this time GDM can develop when maternal insulin production is unable to compensate for the increased insulin resistance, resulting in hyperglycemia.

GDM is more likely to affect those who have risk factors for diabetes mellitus, including obesity, a family history of diabetes, and advanced maternal age.

Like all types of diabetes mellitus, clinical manifestations of GDM include polyuria, or increased urine production; polydipsia, or increased thirst; and polyphagia, or increased hunger.   If left untreated, gestational diabetes can lead to complications. For example, excessive fetal nutrient intake can lead to macrosomia, or large birth weight, and result in the need for cesarean birth.

Screening for GDM occurs between 24 and 28 weeks of gestation by measuring fasting blood glucose levels during an oral glucose tolerance test, or OGTT. The patient is given an oral glucose drink, and their blood glucose is measured at timed intervals. GDM is diagnosed if their blood glucose levels are higher than the defined range.