Gestational Diabetes Mellitus (GDM) is a disorder wherein a pregnant woman develops high blood glucose levels. A study by V. Seshiah and his team from the Diabetes in Pregnancy Study group India (DIPSI) recommends a simple, single-step procedure to screen pregnant women for GDM. Apart from being harmful to the patient, GDM can result in babies who are overweight, who have low blood glucose levels, and who are at a higher risk of developing newborn jaundice. It also increases the risk of developing type II diabetes mellitus in both the mother and child.

The prevalence of GDM in Indian women ranges from 10 to 14.3%, almost two-fold higher than what is seen in western countries. These numbers are steadily on the rise for the last two decades, sparking off concerns among healthcare providers. Nearly half of the women diagnosed with GDM go on to develop type II diabetes mellitus within 5 years of that particular pregnancy. However, if diagnosed early, GDM can be managed through diet restriction, physical exercise, and/​or insulin therapy, depending on the extent of the disorder. 

Despite guidelines from the Government of India, there is a lack of clarity when it comes to screening for GDM at primary healthcare centres. Complex screening procedures and the requirement of fasting prevent many patients from returning to the healthcare centre for a follow-up.

This new study recommends that all pregnant women be screened for GDM. The first screening should be carried out as soon as the woman notifies the doctor about her pregnancy. The team also recommends a single-step procedure for screening an expectant mother for GDM. The woman is asked to drink a solution of 75g of glucose, irrespective of the time of her last meal. She is diagnosed with GDM if, after two hours, her plasma glucose value is greater than or equal to 140mg/​dl.

This straightforward recommendation does not leave anything to speculation and guarantees a uniform testing protocol across the country. Seshiah says, ​“This guideline has been approved by the Ministry of Health, Government of India, as well as by the World Health Organisation, International Diabetes Federation, and the International Federation of Gynaecology and Obstetrics.” He calls the method ​“feasible, sustainable, evidence-based, and cost-effective”. 

Effect of GDM on the health of the fetus

In women diagnosed with GDM, the excess glucose makes its way to the fetus. The fetal pancreatic β‑cells start secreting insulin earlier than normal and in greater quantities to deal with the glucose overload. This enhanced insulin secretion helps the fetus utilize glucose more effectively. As glucose is used up faster in the fetus, more glucose from the mother’s blood pours in, causing more fetal insulin secretion. This sets up a continuous demand-supply loop across the placenta.

Consistently high glucose levels in the mother lead to glucose being excreted into the amniotic cavity via the fetus’s urine. After 20 weeks of gestation, the fetus begins to swallow the amniotic fluid around it. This oral intake of glucose, in addition to the transfer of glucose through the placenta, promotes even greater insulin secretion in the fetus. Prolonged elevations in maternal glucose levels result in an overfed, large fetus.

The consequences of this can be explained using the concept of intra-uterine programming, which states that fetal growth is highly influenced by the prevailing intra-uterine conditions. If there is an imbalance in the uterine environment during fetal growth, this not only affects the development of the fetus, but is also responsible for the development of metabolic diseases later in adulthood. 

The English epidemiologist David Barker explained this phenomenon using his ​‘Fetal Origin of Adult Disease’ theory. The main premise of this hypothesis is the developmental plasticity of the fetus. This means that there are specific time points during fetal development when it is particularly sensitive to the environment. Changes in the intrauterine environment can thus drive physical changes in the fetus. 

In the case of mothers with GDM, due to increased insulin production, the fetus is at risk of accelerated growth in the uterus. For every 1 kg increase in its birth weight, the baby has a 50% increased risk of developing obesity in its adolescence. Thus, by effective screening of women for GDM, we may be able to influence the risk of metabolic diseases over multiple generations. 

GDM in Indian women

A recent study has pointed out that Indian women are more likely to have GDM, lower insulin secretion, and better insulin sensitivity than their Swedish counterparts. The physiological differences can be partly attributed to differences in the genetic makeup of the two populations. 

On the other hand, a slightly older study highlights the role that diet plays against the development of GDM in a pregnant woman. A diet rich in fibre and unprocessed food has been seen to have a protective effect against GDM. 

A genetic propensity towards high blood sugar and GDM, together with their usual rich diet, can be a double-edged sword for pregnant women in India. How can they keep GDM at bay then? Seshiah answers, ​“We have to aim at increasing public awareness about GDM and its implications. This can be done on a scale similar to that of AIDS, Tuberculosis, and Anemia awareness in India. The national health mission can set up campaigns over social media, as well as in newspapers, and television commercials.” 

The detrimental effects of diabetes in pregnancy can last for generations to come. Seshiah reiterates the importance of timely GDM testing with his tagline, ​“Focus on Fetus for the Future!”