The journey of pregnancy can be different for different women. While most sail through the nine months smoothly, a few may experience complications due to their medical history and lifestyle. Though most of these complications resolve on their own, some can be harmful to the mother as well as the baby. One such complication is gestational diabetes, which is characterised by high blood sugar levels during pregnancy. Obesity or genetic predisposition are some of the known risk factors associated with gestational diabetes.

In a recent study, scientists in the United Kingdom established that hot weather could also increase the risk of diabetes in pregnant women. The research also investigated and recorded the impact of COVID-19 on gestational diabetes.

The study: Effect of seasons and COVID-19 pandemic on gestational diabetes 

In the study published in the journal BJOG on 28th May 2021, scientists conducted 4-year long research in their hospital to determine the effect of seasons on the rates of gestational diabetes mellitus (GDM). Scientists further investigated the impact of the COVID-19 pandemic on the cases of GDM.

The incidence of GDM was investigated in more than 28000 pregnant women with the help of an oral glucose tolerance test (OGTT). The participants undertook OGTT before 33 weeks of gestation. The women were assessed for GDM according to the seasons - winter (December to February), spring (March to May), summer (June to August), and autumn (September to November). 

Results of the study

The findings of the study provided insightful statistics:

• Around 12.7% of women tested positive for gestational diabetes. The cases of GDM were higher during the summer months. The scientists reported that 14.78% of women were diagnosed with GDM in summer, while the positivity rate was 11.23%, 12.13% and 11.88% in winter, spring and autumn, respectively.
• During the pre-COVID phase, 12.14% of women were diagnosed with GDM, whereas after the beginning of the COVID-19 pandemic, 16.2% of women were diagnosed with diabetic conditions. This indicated a 33.8% increase in the prevalence of GDM since the onset of the COVID-19 pandemic. 

The possible reason behind this link

Scientists believe that the seasonal change in the blood sugar levels of pregnant women could be related to the metabolism of brown adipose tissue. Brown adipose tissue is a layer of fat that releases heat to maintain the body temperature while balancing blood sugar levels. Several studies indicate that colder temperature improves insulin sensitivity in the body by metabolising the brown adipose tissue. However, with the temperature rise, the fatty tissues do not get metabolised enough, causing increased blood sugar levels to be reported during the summer season. 

Scientists further believe that the increase in the number of cases of GDM post-COVID-19 pandemic may be either due to lack of exercise during the lockdown or stress-induced hyperglycemia.

Studies conducted in the past

Similar studies have been conducted previously that indicate the impact of seasons on the occurrence of gestational diabetes. Some of these studies include:

• Research published in the European Journal of Endocrinology in 2018 evaluated 7,618 pregnant women who went under a 3-hour 100g oral GTT during the third trimester of pregnancy. The results of the study showed that the prevalence of gestational diabetes was 39.2% during the summer season while it was 28.1% during the winter season. 
• A study in the Canadian Medical Association Journal in 2017 examined around 400,000 women for 12 years. Scientists found that the prevalence of gestational diabetes was 4.6% among the women who were exposed to extremely cold temperatures, i.e., equal to or less than minus 10 degree Celsius, 30 days before diabetes testing. On the other hand, the prevalence of gestational diabetes was 7.7% among those who were exposed to hot temperatures, i.e., above 24 degree Celsius. The scientists further concluded that with every 10-degree Celsius rise in temperature, the risk of developing gestational diabetes increased by 6 to 9%.

Who is at increased risk of developing gestational diabetes?

Any pregnant woman can develop gestational diabetes but some factors that can increase the risk of developing the condition include:

• Family history of diabetes
• Diagnosed with prediabetes
• Conceived after the age of 25 years
• Developed gestational diabetes in the previous pregnancy
• Gave birth to a baby weighing more than 4.5kgs in the previous pregnancy
• Body mass index (BMI) at or above 30 indicating obesity or overweight.

How is gestational diabetes managed?

Anti-diabetic medications such as metformin (oral drug) or insulin (injectable drug) may be prescribed to reduce the levels of blood glucose in pregnant women. Besides medications, measures that can help deal with gestational diabetes include: 

• Eating a healthy diet containing larger proportions of vegetables, fruits, whole grains, nuts and seeds. Minimising the consumption of processed foods to control blood sugar levels is advisable.
• Practising aerobic exercises such as walking, swimming, stationary cycling, and dancing for at least 150 minutes a week or 30 minutes a day can improve the utilisation of insulin in the body, thereby reducing blood sugar levels. Exercising during pregnancy should be initiated only after consulting the doctor.
• Checking the blood sugar levels regularly using a glucometer to avoid the complications associated with gestational diabetes. 

Conclusion

With the studies mentioned above, scientists concluded that hot weather can be a trigger for gestational diabetes. However, scientists are yet to identify if this change has a long-term effect on insulin sensitivity or beta-cells of the pancreas, which release insulin in the body. Therefore, it is important for women diagnosed with gestational diabetes to get regular follow-ups to avoid any long-term effects of hyperglycemia after the pregnancy. 

For any diabetes-related query, you can speak with a diabetologist. Also, if you have any questions on the Coronavirus, you can do an online doctor consultation.