Gestational diabetes mellitus

Need for developing case definitions and guidelines for data collection, analysis, and presentation for gestational diabetes mellitus as an adverse event following immunization:

Gestational diabetes mellitus (GDM) is a common condition in pregnancy that can result in significant morbidity and mortality to both mother and fetus. According to the International Diabetes Federation (IDF), about 16.8% of live-births are born to women with hyperglycemia in pregnancy [1]. Approximately 16% of these women will have pre-existing diabetes mellitus, diagnosed prior to pregnancy or during the first trimester of pregnancy. The remainder will have GDM. The incidence of GDM follows the incidence of insulin-resistance and type 2 diabetes mellitus (T2DM) in a given country’s population [2]. The prevalence of GDM can range anywhere from 1% to 15% depending on screening methods used, risk factors and ethnicity [3]. The Global Burden of Disease Project and IDF estimate that the rates of T2DM, including those of reproductive-age women, will continue to rise annually especially in low- and middle-income countries (LMICs) due to increasing risk factors such as obesity and sedentary lifestyle [4].

The pathophysiology for GDM centers around the inability of a pregnant woman to develop an adequate insulin response to a glucose load to maintain her blood sugar in a normal range. This is due to decreasing insulin sensitivity as the pregnancy progresses. Risk factors for GDM include family history of diabetes, GDM in prior pregnancy, ethnicity and obesity. However it has been found that screening based on these factors will miss approximately 50% of women with GDM [5]. GDM places mothers at increased risk for gestational hypertension, pre-eclampsia and cesarean section during pregnancy [6]. In addition, women with a history of GDM are at higher risk for developing T2DM in the future [7]. Fetal complications of pregnancies with GDM include increased risk of macrosomia, operative delivery, shoulder dystocia, birth trauma and neonatal hypoglycemia and hyperbilirubinemia. The Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study demonstrated a continuous association between maternal glucose levels and increased birth weight, cesarean section deliveries and neonatal hyperinsulinemia [8]. In addition, in utero exposure to maternal hyperglycemia may predispose to obesity and insulin resistance later in life [9], [10]. Given the risk for significant maternal and fetal morbidity and mortality in pregnancies complicated by GDM, strict glycemic control during pregnancy is recommended [11], [12] it is also important to be cognizant of medications that may cause transient hyperglycemia or that exacerbate hyperglycemia in mothers with GDM, such as beta-adrenergic agents and corticosteroids that are often administered to women with threatened preterm labor [13].

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