Gestational Diabetes Mellitus: An Overview

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Dr. Kalpataru Halder, Ph.D

Gestational Diabetes Mellitus – An Overview:

Gestational Diabetes Mellitus (GDM) is categorized as a hyperglycemic condition that is diagnosed during the second or third trimester of pregnancy and is distinctive from Type1 and Type2 diabetes. According to International Diabetic Foundation (IDF, 2015), all over the world, 1 in 10 pregnant women are diabetic and 90% diagnosed with GDM. During pregnancy, a woman’s body experiences various biological variations with respect to carbohydrate metabolism (McCabe CF and Perng W, 2017). In a normal pregnancy, insulin resistance develops in the second trimester and continues until birth for providing glucose to the fetus. In equivalent to the reduced sensitivity of maternal insulin, the production of the same by the pancreatic-β increases, resulting in normal glucose concentrations (Sivan E et al, 1997).

GDM can promote significant maternal and fetal complications if pregnant women are not diagnosed or inadequately treated. Further, women with GDM and their offspring are prone to develop Type 2 diabetes in their future life. Maternal complications due to GDM include polyhydramnios, pre-eclampsia, prolonged labor, obstructed labor, cesarean section, uterine atony, post-delivery hemorrhage, infection, and progression of retinopathy which are the leading global causes of maternal morbidity and mortality. Fetal complications might be spontaneous abortion, intra-uterine death, still-birth, congenital malformation, shoulder dystocia, birth injuries, neonatal hypo-glycemia and infant respiratory distress syndrome (Ministry of Health and Family Welfare Report, Govt. of India, 2018).

The major risk factors to develop gestational diabetes are prior history of GDM, obesity, ethnicity or race, polycystic ovary syndrome, family history of Type 2 diabetes, history of uterine overgrown infant, BMI of 25 kg/m2 or greater and increasing maternal age (Chen P et al, 2015). Several studies have also shown that vitamin D deficiency might contribute to the development of GDM (Soheilykhah, S et al, 2010).

GDM is a primary concern in India and approximately 5 million women are affected each year (IDF, 2011). The prevalence of GDM is estimated to be 10-14.3% in India which is much higher than the west. As of 2010, there were an estimated 22 million women with diabetes between age of 20-39 and an additional 54 million women in this age group with impaired glucose tolerance or prediabetes. The frequency of GDM is projected to increase to 20%, i.e., one in every 5 pregnant women is thought to develop gestational diabetes (Ministry of Health and Family Welfare Report, Govt. of India, 2018).

GDM can be recognized in two steps first by screening, followed by diagnostic measures, as required. Screening can be done by monitoring fasting glucose, random glucose or via the glucose challenge test. The glucose challenge test (O’Sullivan JB and Mahan CM, 1964) involves ingestion of 50 gm glucose load and measuring plasma glucose levels after 60 min. However, the World Health Organization (WHO)) recommends a one-step diagnostic procedure using the oral glucose tolerance test (OGTT), where 75 gm of glucose load is used in fasting condition and 2-hour sample is then analyzed.

Few years back, researchers found the impact of a diet with low glycemic index (GI) for managing the risk of GDM (Louie JCY et al, 2013). Glycemic control is improved by avoiding processed/red meat, high-fat diary, and refined grains while favoring vegetables, fruits, whole grains and fish. Carbohydrates with a low GI value (≤55) are slowly digested, absorbed and metabolized (Marsh K et al, 2011). High GI diets result in gestational weight gain, whereas low GI foods are associated with lower birth weight, improved insulin sensitivity, and potentially lower risk for development of GDM (Schoenaker DA et al, 2016). Insulin therapy has been recommended as treatment of both Gestational Diabetes and Diabetes Mellitus. Insulin does not enter the fetal environment and is the only practice approved by the US Food and Drug Administration for treatment of GDM (Denney JM et al, 2018). The use of oral glucose lowering medications such as Glyburide and Metformin during pregnancy is considered contradictory due to various complications to the fetus (Hellmuth E, et al, 1994). Hence, a modification of lifestyle along with insulin therapy can sufficiently help in the treatment and prevention of GDM.


Dr. Kalpataru Halder, Ph.D (Molecular Biology), Sri Satya Sai University of Technology & Medical Sciences, Sehore, Madhya Pradesh, India.

Edited By:

Dr. Nida Rehmani, Ph.D 

Scientific Editor at Bio-Services.


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