Assessment of Triglycerides Levels in Gestational Diabetes-A cross-sectional study

Introduction: Gestational diabetes mellitus (GDM) is the impaired glucose tolerance that is recognized first time during pregnancy. When a woman gets pregnant, glucose intolerance increases and manifests as a positive GDM diagnosis. It has been considered a transient condition because after delivery the majority of cases return to normoglycemic levels. Materials and Methods: This cross-sectional study was conducted in the Department of Obstetrics and Gynecology, Rawal Institute of Health Sciences, Islamabad. Data were collected in a period of 06 months between July 2020 to January 2021. A total of 100 women were included in the study and 5cc of their blood was taken from the vein under aseptic measures for measuring serum triglyceride levels after 12 hours of overnight fasting. Data were analyzed in SPSS version 20.0. Results: The overall mean Serum Triglyceride level of study subjects was 181.17±33.62 mg/dl, with a range of 151-359 mg/dl. Around two-third, 66% of women had <181 mg/dl of Serum Triglyceride level, and 34% of patients had it >181 mg/dl. Our observation was that the mean level of Serum Triglyceride was not different significantly among age, BMI, gestational age, educational and socio-economic groups with p-value >0.05. Conclusion: This study highlights that the circulating mean triglyceride level in GDM subjects was significantly elevated from the normal pregnancy levels.


Introduction
The new onset of glucose intolerance in pregnancy is called GDM. 1 During the second half of pregnancy placental hormones like HPL, progesterone, cortisol, prolactin, and TNF-alpha oppose the insulin effect leading to insulin resistance. This increases the insulin required creating, a diabetogenic, environment. 2 In other words we can say a combination of pancreatic beta-cell insufficiency, insulin resistance with genetic factors manifest as GDM. As in most cases, postpartum blood sugar levels become normal, GDM is considered a 'transient condition'. However, mounting evidence suggests that GDM should be viewed more as a marker for chronic disease. GDM affects 7% of all pregnancies in the US and 2-6% of pregnancies in Europe. 3 Globally, prevalence estimates vary greatly depending on the population studied and the diagnostic test used, from1% among Nigerian women to 19% among women of Chennai, India. 4 Several studies also indicated is parities by race/ethnicity, with higher prevalence among minorities. 5 GDM rates are increasing, with a100% increase in incidence for some ethnic groups compared to 20 years ago. 6 This reflects the increasing incidence of obesity and diabetes even in non-pregnant women. GDM rates tend to follow T2DM rates, and both increased pre-pregnancy BMI and weight gain in adulthood are risk factors for GDM. 7 According to a recent systematic review report overweight women two times and obese women greater than three times are more likely to develop GDM when compared with normal weight women. 8 GDM is accompanied by alterations in pre and postmeal and 24-hour plasma concentrations of glucose, lipids, and amino acids. Clark and colleagues reported that women with GDM have higher triglycerides, free fatty acids, and beta hydroxyl butyrate and lower high-density lipoprotein (HDL) cholesterol than normal pregnant subjects. 9 In one of the study the mean triglycerides (TG) level was found to be 1.83 ± 0.10 mmol/L and the total cholesterol was 5.71 ± 0.24 mmol/L. 10 In another study TG was found to be 216.20 ± 15.18 gm/dl in women with gestational diabetes mellitus. Therefore, women with GDM are at greater risk for developing hypertension, hyperlipidemia, and electrocardiogram abnormalities. 11 The rationale of the study was to estimate the level of TG in GDM cases as local data is scarce on this topic. The aim was to determine the mean level of TG in women with GDM presenting to a tertiary care hospital.

Materials and Methods
This cross-sectional study was conducted in the Department of Obstetrics and Gynaecology, Rawal Institute of Health Sciences, Islamabad. A total of 100 pregnant women were enrolled in a period of 6 months from July 2020 to January 2021. The women between 25-35 years of age, those with gestational age >12 weeks (on dating scan), with singleton pregnancy confirmed on ultrasound, having parity <3 and BMI levels of < 30 kg/m 2 were included in the study. Those women with known DM, hypertension, heart disease, or chronic renal disease were excluded from the study. Women were also excluded if they had a prior history of lipid disorder or metabolic syndrome, were suffering from thyroid diseases, liver diseases, and those women who were taking medications that alter lipid metabolism. Women attending the outpatient departments of Obstetrics and Gynaecology departments were enrolled. Written informed consent was taken from women prior to enrollment. Demographic characteristics as age, gestational age, and BMI were noted.
Moreover, educational status and socioeconomic status were also noted. Women's 5cc blood was taken from the vein under aseptic measures for testing TG level after 12 hours overnight fast and the findings of serum TG levels were noted. SPSS version 20 for Windows was used for data analysis. Mean± SD was measured for the age of the patient, TG levels, gestational age, height, weight, and BMI. Frequency and percentage were presented for qualitative data like Parity, educational status, and economic status. Stratification was done for TG levels <181 mg/dl and >181 mg/dl. The sociodemographic characteristics and gestational history parameters of women were associated with TG categories using t-test for age, gestational age, and BMI and ANOVA for Education and socioeconomic status. A p-value less than or equal to 0.05 was taken as significant. Sample size: Mean ± SD of TG level in women with GDM= 1.83±0.10 mmol/L Confidence Level (C.L) = 95% Absolute precision (d) = 0.05% Sample size (n) = 15, considering stratification the sample size increased to 100 women with GDM on diet control Sampling technique: Non-probability consecutive Results A total of 100 women were evaluated to determine the mean level of triglycerides level (TG) in women with Gestational Diabetes Mellitus. The overall mean age of study subjects was 28.39 ± 2.05 years, with a range of 8 (25-33) years. There were 55% patients of <28 years of age and 45% patients were >28 years. The overall mean weight was 42.05 ± 6.55 Kg, with a range of 33 to 69 Kg. The overall mean height was 154.18 ± 10.73 cm, with a range of 142 to 173cm. The socio-economic status was also assessed and it was observed that 38% of patients belonged to the poor class, 47% of patients belonged to the lower middle class and 15% of patients belonged to the upper middle class. ( (Table 3) Furthermore, the mean triglyceride levels were stratified according to the socio-demographic characteristics of patients. A post-stratification t-test was applied to evaluate a significant difference in mean Serum Triglyceride level between age, gestational age, and BMI groups. ANOVA was applied to evaluate the significant difference of mean Serum Triglyceride level between educational and socio-economic status. There was no significant variation in triglyceride levels according to age, BMI, education, and socioeconomic status of patients. However, higher gestational age was found significantly associated with an increased level of serum triglyceride in women (p-value, 0.04). (Table 4)

Discussion
Women with GDM are at high risk of maternal and fetal complications during pregnancy. Abnormal maternal metabolism affects the growth of the fetus, because diabetes produces changes in maternal metabolic fuels and because diabetic pregnancy is often associated with complications, the effects of maternal diabetes on lipid metabolism are unclear. 12 In the current study, the triglycerides (TG) levels were found higher with a mean value of 181.18 ± 33.62 mg/dl. These results confirmed the previous results reviewed for lipidemia of pregnancy. 13 There is Hyperlipidemia in normal pregnancy and consisting of main triglycerides with smaller rises in cholesterol.
Triglycerides level was studied in normal and GDM pregnancies by Ren Z et al and results reported to show a trend towards being higher in diabetic patients. 14 Their results showed that the mean serum triglycerides concentration for the GDM (2.29 ± 0.074mmol/L) was statistically significantly higher (p<0.001) than controls (1.75 ± 0.083mmol/L). In this study results, there was also an elevation of triglycerides level in GDM cases which is consistent with results reported by many investigators. The current study revealed that women who had GDM had a prevalence rate (34%) of high triglyceride levels. Increased TG during pregnancy occurs due to enhanced hepatic production of very-low-density lipoprotein (VLDL) under the effect of high estrogen. 15 In addition, intestinal absorption of dietary lipid is increased while TG clearance is reduced due to decreased extrahepatic lipoprotein lipase activity. These changes coincide with reduced insulin sensitivity, which may also contribute to the increase in TG levels. 16 This hyperlipidemia including hypertriglyceridemia is pronounced in GDM pregnancies. 17 Maternal insulin sensitivity has a negative association with newborn birthweight. 18 Elevated triglyceride levels are also suggestive of overall elevated risk of cardiovascular disease in women with a history of GDM. Women with prior GDM are known to have a higher prevalence of cardiovascular disease and occurrence of CVD events at a younger age. 19,20 One study shows that there is a link between women GDM or a family history of type 2 diabetes mellitus and their CVD risk. Results from this study showed that women were at a significantly increased risk of developing CVD at a young age. The researchers recommended that cardiovascular interventions should be considered in this group before the advent of disease in order to reduce or prevent the risk of CVD. 20 Studies in other populations have identified risk factors for cardiovascular disease such as hypertension, central obesity, and atherosclerosis, and type 2 diabetes mellitus to be increased in women with prior GDM. 21 Maternal factors such as BMI (body mass index), maternal weight, gestational age, pre-pregnancy lipid levels, and various medical complications of pregnancy may also have significant effects on lipid metabolism and plasma lipid levels. 22 In this study, it was observed that triglyceride level was significantly elevated in lower gestational age. This agreed with a study by Amraei and Azemati who reported a significant increase in the concentration of triglycerides levels in pregnancy complicated by glucose intolerance as compared to normal pregnancy. 23 The advantages of the study lie in the fresh evidence on women with gestational diabetes mellitus and its effect on triglyceride levels. There were some potential limitations of this study. Firstly, there was a short follow-up period which consisted of one GDM review for each patient. This aspect of our study may have affected our results due to existing evidence that the prevalence rate of GDM complications increases with time. In addition, we did not have access to a patient's pre-pregnancy medical history and it is possible that some women had pre-existing diabetes and did not disclose this at the antenatal clinic.

Conclusion
The study highlights and validated that serum triglyceride levels are significantly high in women with GDM. The mean triglyceride level was found more raised in women with high BMI and advanced gestational age. Since the sample was small scale and the study was conducted in an urban setting, the results cannot be generalized. Further large-scale trials in different geographical locations and with rigorous research methods are mandated.