European Journal of Cardiovascular Medicine

Pregnancy induces a natural physiological state of insulin resistance due to the effects of placental hormones, which include human placental lactogen, progesterone, and cortisol. This insulin resistance is a normal adaptive process that allows more glucose to be available for the growing fetus. However, in some cases, this resistance becomes excessive, leading to abnormal glucose metabolism and the development of Gestational Diabetes Mellitus (GDM). GDM is a condition characterized by elevated blood glucose levels that are first recognized during pregnancy and is considered a major health concern in obstetric care. It is a significant cause of morbidity for both the mother and the fetus, often requiring close monitoring and management during pregnancy (1).

In India, the prevalence of GDM varies widely, ranging from 3.8% to 21%, depending on the diagnostic criteria and methods used in different studies (1). This wide variation can be attributed to factors such as the population's demographics, regional healthcare access, and the specific diagnostic tests employed. More importantly, the increasing burden of GDM reflects broader global trends, particularly in low- and middle-income countries. According to projections by the United Nations Population Division (UNPD) for the year 2025, the World Health Organization (WHO) anticipates a significant rise in the number of people with diabetes worldwide, especially among women. These projections suggest that the prevalence of GDM will continue to increase, particularly in less affluent regions, further exacerbating the health burden of maternal and neonatal complications associated with uncontrolled hyperglycemia during pregnancy (2).

Maternal hyperglycemia, whether pre-existing or gestational, is a well-established risk factor for fetal morbidity. It has been linked to a higher incidence of complications such as macrosomia (large birth weight), preterm birth, and increased perinatal mortality. For the mother, GDM can lead to conditions such as preeclampsia, urinary tract infections, and an increased risk of developing type 2 diabetes later in life. Women who are unable to produce sufficient insulin to overcome the insulin resistance caused by pregnancy are at a higher risk of developing GDM. This inability to maintain glucose homeostasis during pregnancy may be influenced by genetic predispositions, lifestyle factors, and preexisting medical conditions such as obesity, polycystic ovary syndrome (PCOS), or a family history of diabetes (3). Consequently, GDM represents a complex interplay of metabolic, hormonal, and environmental factors that requires careful management to reduce adverse outcomes for both the mother and child.

As the prevalence of GDM continues to rise, especially in developing countries like India, understanding the contributing risk factors and effective prevention strategies becomes increasingly important. This condition not only impacts the immediate health of the pregnant woman and her baby but also poses long-term health risks, which makes early screening and intervention critical for improving maternal and neonatal outcomes.

A cross-sectional institutional-based study was conducted to determine the prevalence of Gestational Diabetes Mellitus (GDM) among pregnant women attending the outpatient department (OPD) of SCB Medical College and Hospital in Cuttack, Odisha, India. The study was carried out over a one-year period, from July 2018 to June 2019. A total of 483 pregnant women were screened for signs of diabetes mellitus who had no prior diagnosis of diabetes. The screening was conducted with the voluntary consent of the participants, all of whom agreed to undergo the glucose challenge test at the hospital's dedicated Diabetes Centre.

Inclusion in the study was restricted to those women who had no history of diabetes prior to pregnancy. Pregnant women with pre-existing diabetes were excluded from the study to ensure that only those with GDM were considered in the analysis. Each participant underwent a 75 g, 2-hour oral glucose tolerance test (OGTT), as per the standard protocol, and the diagnosis of GDM was made using the criteria established by the World Health Organization (WHO). According to the WHO, a diagnosis of GDM is confirmed when the plasma glucose level at 2 hours post-glucose intake is ≥ 140 mg/dl (4). This diagnostic threshold was used to identify individuals with GDM in the study. According to recent data, the prevalence of GDM in India, as determined by the WHO 2-hour plasma glucose criteria (≥ 140 mg/dl), was found to be 16.55% (5).

Statistical Analysis

Data analysis was performed using the R software. The Chi-square test was employed to assess the association between categorical variables. A p-value of less than 0.05 was considered statistically significant, indicating that the results were unlikely to have occurred by chance alone. This statistical approach allowed for the determination of significant relationships between risk factors and the prevalence of GDM in the study population.

The prevalence of Gestational Diabetes Mellitus (GDM) varied across different age groups. The highest prevalence was observed in the 25-29 age group, with 23.7% of the women in this group diagnosed with GDM. The 15-19 age group had the lowest prevalence at 9.0%. Overall, the prevalence of GDM was 15.9% across all age groups. Statistical analysis revealed no significant association between age and the prevalence of GDM (χ² = 5.351, DF = 3, p = 0.234).

Table I: Prevalence of GDM According to Age of the Subjects

χ² = 5,351; DF = 3; p = 0.234.

The prevalence of GDM was significantly higher among women with a family history of diabetes. Among women with both parents diabetic, the prevalence was 49.4%, compared to 27.3% for those with a single parent diabetic, and 23.4% for women with no family history of diabetes. However, no statistically significant association was found between family history and the prevalence of GDM (χ² = 3.481, DF = 3, p = 0.211).

Table II: Prevalence of GDM According to Family History of Diabetes

χ² = 3.481; DF = 3; p = 0.211.

Women with a history of "good" obstetric outcomes (276 women) had a higher prevalence of GDM (21.0%) compared to those with "bad" obstetric history (207 women), where the prevalence was 9.2%. The association between obstetric history and GDM was found to be statistically significant (χ² = 21.234, DF = 2, p = 0.001).

Table III: Prevalence of GDM According to Previous Obstetric History

χ² = 21.234; DF = 2; p = 0.001.

Diet patterns had a significant impact on the prevalence of GDM. Among the 77 women with GDM, 39% were vegetarian, while 61.0% were non-vegetarian. In contrast, among the 406 non-GDM women, 66.7% were vegetarian and 33.3% were non-vegetarian. This difference in diet pattern between GDM and non-GDM women was statistically significant (χ² = 16.661, DF =2, p = 0.001).

The prevalence of GDM was significantly higher among women with higher BMI. Women classified as obese (BMI ≥ 30 kg/m²) had the highest prevalence of GDM at 45.7%, followed by overweight women (BMI 25-29.9 kg/m²) at 20.0%. The prevalence was lowest in the normal BMI group (18.5-24.9 kg/m²) at 5.7%. This association between BMI and GDM was statistically significant (χ² = 51.534, DF = 3, p = 0.001).

Table V: Prevalence of GDM According to Body Mass Index (BMI)

χ² = 51.534; DF = 3; p = 0.001.

Physical activity patterns were also associated with the prevalence of GDM. Among the 77 women with GDM, the majority (57.1%) did not engage in any physical activity. In contrast, 39.4% of non-GDM women regularly exercised, and only 34.0% reported no physical activity. A significant association was found between physical activity and GDM, with inactive women having a higher prevalence of GDM (χ² = 12.500, DF = 3, p = 0.001).

Table VI: Prevalence of GDM According to Physical Activity

χ² = 12.500; DF = 3; p = 0.001.

Gestational diabetes mellitus (GDM) is the most prevalent medical complication during pregnancy, carrying significant risks for both maternal and fetal health. Women diagnosed with GDM are at increased risk for several complications, and their infants face a higher likelihood of morbidity and mortality. The prevalence of GDM is notably high within the Indian population (6). Various factors have been identified as influencing the risk of GDM, including obesity, a family history of diabetes in first-degree relatives, infertility treatments, polyhydramnios, recurrent urinary tract infections (UTIs), stillbirth history, the delivery of large infants (>4 kg), unexplained neonatal death, pre-eclampsia in multiparous women, and advancing maternal age (7).

This study offers valuable insights into the factors associated with GDM, which could aid in the development of early preventive measures. Among the pregnant women surveyed, 77 (15.9%) were diagnosed with GDM. The highest prevalence of GDM was observed in the 25-29 age group 30 (23.7%), compared to other age groups. Our results also indicated that women with a family history of diabetes were more likely to develop GDM than those without such a history. Specifically, women with both parents diabetic exhibited a significantly higher prevalence 38 (49.4%) than those with only one parent diabetic 18 (23.4%). These findings are consistent with a similar prospective case-control study conducted in China in 2005, which found that a family history of diabetes significantly increased the risk of GDM (8). This association has been corroborated by other studies as well (9,10). Additionally, women with a good obstetric history (GOH) demonstrated a higher prevalence of GDM (21.0%), a result that aligns with findings from a population-based longitudinal study, which reported an increased frequency of mild pre-eclampsia and chronic hypertension with superimposed pre-eclampsia among women with GDM (11,12).

Diet composition is a modifiable risk factor for abnormal glucose tolerance during pregnancy. Previous studies have shown that diets high in total fat, saturated fat, red and processed meats, and those with a high glycemic load increase the risk of GDM, while polyunsaturated fats, carbohydrates, and fiber have protective effects (13). In our study, non-vegetarian women (61.0%) had a higher likelihood of developing abnormal glucose tolerance, which may be attributed to a diet rich in fat and calories and low in fiber. These results were statistically significant. Several recent studies have examined diet quality as a modifiable risk factor for GDM (14-17). Notably, Saldana et al. reported that higher fat intake and lower carbohydrate intake were associated with an increased risk of GDM and impaired glucose tolerance (IGT). Furthermore, high fiber intake, which has been linked to a reduced risk of type 2 diabetes mellitus (DM) in non-pregnant adults, was found to lower the risk of GDM in two studies (20-24).

The relationship between body mass index (BMI), exercise, and GDM has been widely studied. Our findings suggest that women with a BMI of 33 or lower had similar GDM rates, regardless of whether they exercised during pregnancy. However, women with a BMI greater than 33 who engaged in physical activity had lower GDM rates compared to overweight women who did not exercise. This highlights the importance of exercise and the association between adiposity and GDM. Aerobic exercise in obese individuals has been shown to reduce hyperinsulinemia and lower fasting plasma glucose levels. As insulin sensitivity improves, hepatic glucose production is suppressed, and insulin-stimulated glucose uptake increases, potentially reducing the likelihood of GDM in overweight or obese pregnant women (25).

Our study also confirmed that the prevalence of GDM was highest 37 (45.7%) among women who were obese before conception, followed by 24 (20.0%) in overweight women, compared to 16 (5.7%) in women with an ideal BMI. This result was statistically significant. Given these findings, exercise has been recommended as an effective therapeutic intervention for managing GDM and preventing diabetes (26). Moreover, regular physical activity during pregnancy has been shown to reduce the need for insulin therapy in women with GDM (27). Despite initial concerns about the potential risks of exercise during pregnancy, research has consistently demonstrated that physical activity is both safe and beneficial (28). Physical activity plays a crucial role in maternal carbohydrate metabolism, and our study found that sedentary women had the highest prevalence of GDM 44 (57.1%) compared to those with irregular 21 (27.3%) or regular physical activity 12 (15.6%). A cohort study of over 1,800 pregnant women showed that those who were physically active before and during pregnancy had a significantly reduced risk of developing GDM and impaired glucose tolerance. Walking, in particular, appeared to offer protective benefits, while a sedentary lifestyle was associated with increased risk. These findings further support the protective effect of physical activity against the development of diabetes, a benefit that has been well-established among non-pregnant adults and men (29-31).

The increasing prevalence of GDM in India presents a growing public health challenge. Early screening for glucose intolerance, the management of euglycemia, maintaining a balanced diet, regular physical activity, and consistent antenatal care are essential measures to reduce the rising incidence of GDM and improve maternal and fetal outcomes.

Given the rising prevalence of GDM in India, especially among women with higher BMI and poor dietary and physical activity habits, there is an urgent need for targeted interventions. Early screening, coupled with lifestyle modifications such as maintaining a healthy weight, improving dietary habits, and engaging in regular physical activity, can significantly reduce the risk of GDM and its associated complications. Furthermore, continued research and public health initiatives are essential to address the increasing burden of GDM and to ensure better maternal and neonatal health outcomes.

In conclusion, GDM presents a complex interplay of genetic, environmental, and lifestyle factors, and effective management requires a multi-faceted approach. Preventive strategies, including timely screening, lifestyle modifications, and proper antenatal care, are crucial in mitigating the growing health burden posed by GDM, particularly in low- and middle-income countries like India.

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