Are you pregnant? Are you a non-vegetarian? Do you live in a city with very poor ambient air quality due to vehicular pollution? These might sound like random queries but if your answer is in the affirmative to all three of them, then it is time to adopt a healthier lifestyle as you could be facing a higher risk of developing gestational diabetes.
Gestational diabetes is a condition developed during pregnancy where the expectant mother’s blood develops high blood glucose not because of insulin deficiency but mainly due to insulin resistance triggered by hormonal changes, especially in their placenta to ensure proper nutrition to the foetus growing in their womb. Though it is generally considered to be reversible post-delivery, experts claim that there has been an increase in the number of women with diabetes-related complications during childbirth developing type 2 diabetes a couple of years after childbirth.
“Despite mandatory diabetes screenings during pregnancy, we continue to come across numerous cases of GDM regularly. Though normally GDM gets reversed after childbirth, it does not happen all the time and could often lead to complications to the baby,” said Dr Banshi Saboo, an Ahmedabad-based diabetologist and former president of the Research Society for Study of Diabetes in India (RSSDI).
Multiple blood glucose management studies across the globe have already established separately that prolonged exposure to air pollutants, especially from vehicular pollution, and an overdependence on animal-protein-based food in daily diet are among the main modifiable high-risk factors that could trigger a spike in blood sugar levels. The simplest explanation offered to this is that these toxic pollutants, mainly from vehicular emissions, cause systemic inflammation that could lead to vascular chemical imbalance and hormonal disruptions with a direct bearing on insulin resistance resulting in the blood glucose levels to soar.
Dietary pattern + air pollution = higher risk of GDM
In 2021 a group of researchers from China conducted and published a study on GDM and claimed that dietary patterns with a high quantity of processed or unprocessed meat and animal proteins could aggravate the adverse effects of air pollution and lead to a higher risk of developing gestational diabetes.
Based on the North East Cohort Study of China (NEC-Biobank), the researchers from Liaoning province conducted a detailed survey of 2,244 pregnant women during their first, second and third trimesters of pregnancy between 2018 and 2019 with a subsequent three-year follow-up before arriving at a conclusion for their study. The findings were published in the February 2021 edition of Environment International Journal.
The research team prepared a database of pre-delivery dietary patterns of these women at least a year before their pregnancy. Pollution data was obtained from 78 air-quality monitoring stations, including levels of nitrogen dioxide, sulphur dioxide, carbon monoxide, ozone and suspended particulate matter levels. The food choices of the participants were compiled and classified under four categories: healthy dietary pattern, sweet-based diet, animal protein diet and traditional Chinese dietary pattern.
The researchers arrived at a conclusion that the toxins mixed in our bloodstream from polluted air interact with the type of food, especially animal proteins, and trigger vascular conditions leading to gestational diabetes. The main reason pointed out is that the systemic inflammation and oxidative stress caused due to prolonged exposure to gaseous pollutants — like nitrogen dioxide and sulphur dioxide — gets further aggravated in meat eaters. This could push them into a high-risk category compared to those residing in the same area but with a different dietary routine or vice versa.
“Associations between exposure to air pollution caused by nitrogen dioxide, sulphur dioxide and PM2.5 and an increased gestational diabetes risk might be a result of the biological effects of oxidative stress caused by these pollutants generated from small combustion sources,” the study said.
A study from Iceland — published in September 2016 in Obesity, the research journal of the Obesity Society — pointed out that C–Reactive protein could function as an inflammatory agent in pregnant women. Meat products are rich in C Reactive protein, which could increase the rate of systemic inflammation in the blood, thereby increasing blood glucose levels of the individual. The presence of lead in pickled eggs was also attributed as another inflammatory agent that acted upon the effect of toxic pollutants and increased the risk of gestational diabetes in pregnant women. Frequent consumption of non-vegetarian food before pregnancy was attributed as a reason for rise in body mass index (BMI) which in turn could have an upward ripple effect on the blood sugar and GDM risk levels during pregnancy.
However, the study did not consider the effect of pollution caused due to black carbon (soot) and particulate organic matter.
Numerous research articles have claimed that a Mediterranean diet could bring down the risk of developing diabetes at childbirth and subsequent complications. Mediterranean diet is the term used to describe plant-, fish- and nuts-based nutritious diet prepared in olive oil. As the name suggests this dietary pattern is generally followed in Mediterranean countries like Greece and Italy and it is also found good for reducing other cardiovascular complications.
“Mediterranean diet is good for diabetics, and it is also very healthy as it includes food with Omega-3 fatty acids that play a vital role in reduce inflammation and prevents vascular complications in both diabetics and non-diabetics alike,” said Dr Tom Babu, head of the diabetes division and consultant endocrinologist, Silverline Hospitals, Kochi.
What is gestational diabetes?
According to Johns Hopkins Medicine, gestational diabetes is caused when placental hormones that play an integral role in foetal nourishment end up compromising the insulin sensitivity in the mother’s blood, leading to an excess build-up of blood glucose. The main hormones responsible for this are estrogen, cortisol and placental lactogen that block the insulin produced inside the mother’s body from breaking down blood glucose leading to an excess deposit of blood sugar in her blood. This condition that normally develops 20 to 24 weeks into pregnancy is called contra insulin effect. As the foetus develops, more placental hormones get secreted and it eventually exceeds the insulin-production level, leading to gestational diabetes and high blood glucose levels.
The nutritional requirements of the foetus increase considerably during late stages of pregnancy which will trigger excess secretion of maternal hormones in the placenta, especially progesterone, estrogen and lactogens. It has been pointed out that the rate of estrogen secretion in a pregnant woman is more than what a normal ovulating woman would secrete in 150 years.
The increase in these maternal hormones also result in a proportional increase in insulin resistance in the mother’s blood which eventually leads to gestational diabetes. Though it is generally believed that would be reversed after childbirth there have been numerous cases where the woman either ends up developing prediabetes requiring lifelong blood glucose level management or either type 2 diabetes itself within five years of the delivery date.
“I have seen numerous women who get affected with gestational diabetes and often require a strict blood glucose level monitoring and a healthy balanced diet after childbirth to ensure that they do not develop type 2 diabetes later on in life,” said Dr Saboo. He said in India most women face the risk of developing gestational diabetes during their late 20s or early 30s when they often decide to have their second child.
Gestational diabetes and the newborn baby
Gestational diabetes directly affects the unborn child as the foetus receives all its nutrients from the mother’s blood. Women with this condition will have more glucose content in their blood which gets misread by the pancreas of the foetus to produce more insulin. This additional insulin ends up converting the excess glucose in the blood and depositing it as fat in the foetus. This increases the chances of the child being overweight than regular babies at childbirth. This condition is called macrosomia and it often leads to a complicated childbirth procedure requiring surgical intervention. Children born to mothers with gestational diabetes are also found to have a tendency to develop obesity later in life. If the mother has high blood sugar levels, then the foetus will often have high insulin levels which in turn could lead to hypoglycaemia (low blood sugar) in the baby during delivery and the glucose level will have to be immediately stabilized after the delivery.
According to the US Centers for Disease Control and Prevention, at least 50 per cent of women with GDM tend to develop type 2 diabetes later in their life. Experts attribute this alarming scenario to various lifestyle choices and modifiable external risk factors that trigger insulin resistance in their vascular system.
