Pregnancy induces progressive changes in maternal carbohydrate metabolism. As pregnancy advances, insulin resistance and diabetogenic stress due to placental hormones necessitate compensatory increase in insulin secretion. When this compensation is inadequate, gestational diabetes develops.
Gestational diabetes mellitus (GDM) is defined as hyperglycaemia first recognised during pregnancy. GDM is not only related to perinatal morbidity but also to an increased risk of diabetes and cardiovascular disease in the mother in later life and to childhood obesity in the offspring.
It is estimated by the International Diabetes Federation that 21.1 million (16.7%) of live births in women in 2021 had some form of hyperglycaemia in pregnancy. Of these, 80.3% were due to gestational diabetes mellitus (GDM), while 10.6% were the result of diabetes detected prior to pregnancy, and 9.1% due to diabetes (including type 1 and type 2) first detected in pregnancy.
There are some regional differences in the prevalence of hyperglycaemia in pregnancy with the South-East Asia region having the highest age adjusted comparative prevalence at 28.0%, compared to 8.6% in the Middle East and North Africa region. The vast majority (87.5%) of cases of hyperglycaemia in pregnancy are seen in low and middle-income countries, where access to antenatal care is often limited.
Prevalence of hyperglycaemia in pregnancy, as a proportion of all pregnancies, increases rapidly with age, with the highest prevalence (42.3%) in 45 to 49-year-old women, although there are fewer pregnancies in this age group. Of course, this age group also has a higher prevalence of diabetes among non-pregnant women. As a result of higher fertility rates in younger women, half (46.3%) of all cases of hyperglycaemia in pregnancy (9.8 million) occur in women under the age of 30 years.
Women who develop gestational diabetes during pregnancy have a greater chance of developing type 2 diabetes. Women who had gestational diabetes while pregnant are also at a higher risk of developing metabolic syndrome and heart conditions compared to women who had normal sugar levels during pregnancy.
Research done in the Canadian province of Saskatchewan revealed that gestational diabetes resulted in type 2 diabetes in 19-30% of residents.
Yet another research showed that when youngsters developed diabetes (47.2%), it was linked to the mother having had gestational diabetes.
In the current scenario, with early diabetes onset and late pregnancies, more women are expected to enter pregnancy after being diagnosed with diabetes.
GDM during pregnancy increases the risk of the child developing complications like macrosomia, hypoglycaemia, jaundice, respiratory distress syndrome, polycythaemia and hypocalcaemia. In addition to this, there is also an increased chance of obesity, reduced glucose tolerance, overt diabetes and hyperlipidaemia. Further, for the girl child, the chances of pre-GDM and GDM also rises.
Hence, there is a need to start preventive treatment from conception itself. Women with gestational diabetes should be given special attention for reducing the overall incidence of diabetes. Pregnant women should be screened for GDM and timely treatment commenced when indicated. Providing appropriate treatment brings down mortality and reduces the chances of developing conditions like diabetes, stroke, hypertension, obesity and cardiovascular diseases.
Pregnancy is a window period and the occurrence of GDM during pregnancy represents an opportunity to reduce short and long-term risk of adverse health outcomes in the mothers and their children.
Dr. K. Baraneedharan Senior Consultant Diabetologist Kauvery Hospital Chennai
