Gestational Diabetes Mellitus is defined as carbohydrate intolerance of variable severity with onset or first recognition during pregnancy, according to WHO guidelines. ^[1] Gestational Diabetes Mellitus is “any degree of glucose intolerance that either starts during pregnancy or is newly diagnosed in pregnancy” as per ACOG (American College of. Obstetrics and Gynaecology). ^[2] It includes women, whose glucose tolerance, is normal after pregnancy and those with type 2 diabetes with persistent glucose in intolerance developed later. ^[3]

The GDM incidence is nowadays increasing due to life style changes, increased obesity and metabolic syndrome prevalence. The trend towards modern life style, older age at child birth, changing eating habits and reduced physical activity has now lead to increased GDM incidence. ^[4] History of diabetes in family (like father, mother, maternal uncle and aunts, and in siblings too). In addition to all above factors, ethnicity also plays a role in the development and risk of GDM. ^[5] Our Indian ethnicity is more prone for developing Diabetes in the Gestational period. Moreover as India is in the trend towards adoption of western life style among youngsters, this risk factor adds an additional impact in the development of GDM^.[6]

The incidence of GDM is increasing globally and is now 20% to 27% of all pregnancies. According to Indian diabetic federation, in 2015, two out of every five diabetic women, are of reproductive age, accounting for women over 60 million worldwide. According to this estimate, 16.2% of live births, who delivered in 2015 had some form of, hyperglycemia in pregnancy. In that GDM accounted for 85.1%. Gestational diabetes affects one in seven births. ^[7] For a successful pregnancy outcome, the longitudinal changes, that takes place, in carbohydrate metabolism during pregnancy plays an integral role. Gestational diabetes mellitus is an important cause of perinatal mortality and morbidity.^[8] The complications occurring due to GDM are preventable if screening and diagnosis is done at an early stage as possible. ^[9]

The complications arising in GDM is mostly preventable if adequate control of blood sugar levels are maintained throughout the pregnancy. As it is always good that prevention is better than cure, it is better to prevent its occurrence than to deal with it after its onset. Gestational diabetes poses short term as well as long-term effects on the health of both the mother and the child. Hence early diagnosis and treatment is necessary to decrease the risksHigh frequency of GDM among Indian women needs early diagnosis of GDM. ^[10]There is no specific biochemical test so far available that can predict the risk of developing GDM other than the blood sugar tests with OGCT, OGTT etc. Recent studies have shown a positive correlation between moderately elevated serum ferritin levels in mid trimester of pregnancy and increased risk of GDM. ^[11]

Insulin resistance plays a key role in GDM and there is a systemic inflammation, indicated by higher levels of C-reactive protein & interleukin-6. Adipocytes in adipose tissue can secrete pro inflammatory cytokines in obesity which is also associated with insulin resistance^.[12] Serum ferritin, is a major storage protein of iron. It is also a acute phase reactant which increases in inflammatory conditions. Studies have shown a positive relation between insulin resistance and serum ferritin levels. The role of serum ferritin as an inflammatory marker is used in this study and its levels are measured in mid pregnancy to predict the risk of developing GDM, thereby making it as a tool for early diagnosis and prevention.^[13]

This case-control study was conducted at Department of Biochemistry, Mamata Medical College over a period of 1 year. A total of 360 pregnant women were enrolled in the study, including 180 women with gestational diabetes mellitus (GDM) and 180 healthy, age-matched pregnant women. The participants were recruited serially at 24–28 weeks of gestation.

Women with acute or chronic inflammatory or infectious diseases, a history of malignancy, diabetes mellitus (DM), seizure disorders, acute or chronic liver disease, acute or chronic renal disease, drug or alcohol abuse, or iron deficiency anemia were excluded from the study.

Per the national policy, all participants continued perinatal iron supplementation throughout the pregnancy, with (each woman receiving a standardized dosage of 50 mg of elemental iron per day), starting from the fourth month of pregnancy. Prepregnant weight was used to calculate body mass index (BMI, weight in kilograms divided by the square of height in meters). Blood pressure was measured with the subject seated using a random zero sphygmomanometer. Blood pressure was measured twice on the left upper arm, and the average of the two measurements was used for analysis.

A two-step approach was applied to diagnose GDM. All the women were initially screened by the glucose challenge test with 50 g glucose at 24–28 weeks of gestation. A three-hour oral glucose tolerance test was performed for women with plasma glucose concentrations exceeding 130 mg/dL on a glucose challenge test. The fasting plasma glucose concentration of the diagnosing oral glucose tolerance test was used as the mid-pregnancy fasting plasma glucose in this study.

Blood samples of the participants were collected at 24–28 weeks of pregnancy after at least 12 hours of fasting. Plasma glucose was measured by the glucose peroxidase colorimetric enzymatic method, with a sensitivity of 5 mg/dL. Glycosylated hemoglobin (HbA_1c) (normal range 4.8%–6.2%) was measured by ion exchange chromatography with DS5. Complete blood count was performed for all the participants using a hematologic analyzer. C-reactive protein was measured by a high-sensitivity assay, with the use of the latex particle-enhanced immunoturbidimetric assay, with an analytical sensitivity of 0.175 mg/dL and an upper limit of normal of 5 mg/dL. Serum ferritin was measured by a coated-tube immunoradiometric assay. The assay was performed in duplicate. The interassay coefficients of variation ranged from 2% to 4%. Electrochemiluminescence immunoassay was used to detect serum insulin concentrations. The sensitivity of the assay was 1.3 pmol/L.

All the participants were followed until delivery, and their pregnancy outcomes were recorded. All subjects with rupture of membranes prior to 37 weeks’ gestation were considered to have preterm premature rupture of membranes. Preterm labour was defined as the presence of uterine contractions of sufficient frequency and intensity to affect progressive effacement and dilation of the cervix prior to term gestation (20–37 weeks). Dystocia was considered in subjects with difficult parturition to the point of needing human intervention due to large fetal size.

In women with GDM an additional two-hour oral glucose tolerance test with 75 g of glucose was performed eight weeks after delivery. The oral glucose tolerance test results were interpreted based on World Health Organization criteria. All the participants were notified about the goals of the study, and informed consent was obtained.

Statistical analysis

Data are presented as mean ± standard deviation. Proportions were compared using the Chi-square test. Group means were compared using the Student’s t-test and analysis of variance (ANOVA). The Mann-Whitney test was used for variables without a normal distribution. We also used log transformation for the variables without normal distribution, like ferritin and C-reactive protein. The Pearson correlation statistic was used to examine the relationship between elevated serum ferritin and BMI. An odds ratio (OR) was calculated to compare the risk of GDM in people with higher ferritin levels. The conditional logistic regression analyses were performed to determine the influence of elevated serum ferritin on the risk of GDM and pregnancy morbidities. A significance of P < 0.05 was used for all statistical tests.

In the present study, 360 gravid women, whose serum ferritin level was estimated at 24 to 28 weeks, were followed up with repeat screening for GDM in the third trimester. Among them, 71 (19.7%) were diagnosed with GDM during the follow-up period.

The present study assessed baseline demographic characteristics between the GDM (n = 77) and non-GDM (n = 311) groups. The mean age of participants in the GDM group was 28.0 ± 5.2 years, while in the non-GDM group, it was 27.0 ± 4.4 years, with a p-value of 0.087, indicating no significant difference between the groups.

Table-1: Baseline Demographic Characteristics in the Present Study

The mean gestational age was 27.1 weeks in the GDM group and 25.1 weeks in the non-GDM group, with a p-value of 0.277, suggesting no statistically significant difference.

Table-2: Distribution of Study Patients by Age (n=360)

Table -3: Parity Distribution of Study Participants (n=360)

In the present study, among 360 participants, the GDM group had 33.8% primigravidas and 66.2% multigravidas, while the non-GDM group had 44.7% primigravidas and 55.3% multigravidas. The p-value was 0.082, indicating no statistically significant difference. Therefore, the parity distribution was comparable between both groups.

Table-4: Hemoglobin and Serum Ferritin Distribution in Study Participants (n=360)

The mean hemoglobin levels in the GDM and non-GDM groups were 12.2 gm% and 11.7 gm%, respectively, with a p-value of 0.665, indicating that both groups were comparable in terms of hemoglobin levels.

Table-5: Comparison of Serum Ferritin Levels with GDM (n=360)

The mean hemoglobin levels were comparable in both groups (p = 0.665, not significant).

The mean serum ferritin level was significantly higher in the GDM group (p = 0.001), indicating it as a risk factor for GDM. A higher serum ferritin level was associated with an increased risk of GDM (p < 0.001, statistically significant).

Table-6: Hemoglobin and Serum Ferritin Distribution in Study Participants

In this study, we evaluated the baseline demographic characteristics of pregnant women diagnosed with gestational diabetes mellitus (GDM) compared to those without GDM. Our findings revealed no significant differences in age, parity, gestational age, or hemoglobin levels between the two groups, suggesting that these factors may not independently contribute to the development of GDM.^[14]

The mean age of women in the GDM group was 28.0 ± 5.2 years, which was slightly higher than the 27.0 ± 4.4 years observed in the non-GDM group. However, the p-value of 0.087 indicated that the difference in age was not statistically significant. This is consistent with other studies that have shown age to be a risk factor for GDM, but the results from our study did not support a significant correlation between age and GDM diagnosis.^.[15]

The aim of present study was to; compare serum ferritin level between two groups and to evaluate any association between serum ferritin level and GDM. In this present study, it was observed that 70.0% patients belonged to age 20-30 years in Group A and 80.0% in Group B. The mean age was 29.5±4 years in Group A and 28.1±4.4 years in Group B. The difference was statistically not significant (p>0.05). In this current study 70.0% patients had multipara in Group A and 39(65.0%) in Group B. And the mean duration of gestation was 29.3±3.6 weeks in Group A and 27.6±3.5 weeks in Group B, which were almost similar between two groups. A significant correlation between higher serum ferritin levels and insulin resistance syndrome has been showed ^[16]. Some studies revealed a significant association between higher serum ferritin and risk of type 2 diabetes.^[17]

Present study also confirmed that the mean serum ferritin levels were121.1±17.7 ng/ml in Group A and 86.4±19.9 ng/ml in Group B, which is significantly (p<0.05) elevated in Group A. In one study showed that in pregnant women with gestational diabetes, the serum ferritin level was found to be higher (41±35 in GDM and 35.5±30.7 in non GDM) in comparison with healthy pregnant women and the difference was statistically significant (p<05) ^[18]. The risk of type 2 diabetes is increased when the level of ferritin is elevated.^[19] Serum ferritin levels were significantly elevated in GDM with compared to non GDM group also observed by many investigators.

The result found in the present study, that 65.0% patients had serum ferritin level >120 ng/ml in Group A and 20.0% in Group B. Serum ferritin level >120 ng/ml had 3.1 (95.0% C.I. 1.6 to 7.60) times significantly (p<0.05) increase to developed gestational diabetes mellitus with compared to healthy pregnant women. In a study showed that the risk of having GDM with these high level of ferritin to be 1.4-fold higher than that in subjects with lower ferritin concentrations having OR 1.4 with 95% CI= 1-1.87 (P<0.05) ^[20]. The investigators also reported that after adjusted for age Odds Ratio was 1.38 (95% CI=1.02-1.86) (p<0.05)  The risk of having GDM to be more than two fold higher than the risk for those with lower concentrations of ferritin were also observed.^[21] The above findings are closely resembled with the present study.

Serum ferritin is significantly higher in GDM when compare with non GDM women. Thus high serum ferritin may be considered as a risk factor for the development of GDM. ^[22,23]

After doing a comprehensive analysis of all the above observations, the fnal conclusion that can be drawn from the present study is that the GDM women have higher level of serum ferritin as compared to normal glucose tolerant pregnant women. Because of its association, it can be used as a biomarker in early gestation for the prediction of development of GDM later in pregnancy. Serum ferritin is an economical and feasible option as early prediction of GDM, which helps us to intervene early in the form of dietary modifcation and lifestyle changes and protect pregnant women from diabetes-related morbidities and perinatal morbidities.

1. American Diabetes Association: Gestational diabetes mellitus. Diabetic care defnition and diagnosis of Diabetes mellitus and intermediate hyperglycemia. World Health Organization. 2001;23(1):S77–S79.
2. Government of India. Maternal and Health Division, Diagnosis and Management of Gestational Diabetes Mellitus: Technical and Operational Guidelines. New Delhi, India: Ministry of Health & Family Welfare. New Concept Information Systems. 2018.
3. Chen X, Scholl TO, Stein TP. Association of elevated serum ferritin levels and the risk of gestational diabetes mellitus in pregnant women: The Camden study. Diabetes Care. 2006;29(5):1077–82.
4. Kell DB, Pretorius E. Serum ferritin is an important infammatory disease marker, as it is mainly a leakage product from damaged cells. Metallomics. 2014;6(4):748–73.
5. Fernández-Real JM, Ricart-Engel W, Arroyo E, et al. Serum ferritin as a component of the insulin resistance syndrome. Diabetes Care. 1998;21(1):62–8.
6. Catalano PM, Tyzbir ED, Roman NM, et al. Longitudinal changes in insulin release and insulin resistance in nonobese pregnant women. Am J Obstet Gynecol. 1991;165(6):1667–72.
7. Radaelli T, Varastehpour A, Catalano P, et al. Gestational diabetes induces placental genes for chronic stress and infammatory pathways. Diabetes. 2003;52(12):2951–8.
8. Kirwan JP, Hauguel-De Mouzon S, Lepercq J, et al. TNF-alpha is a predictor of insulin resistance in human pregnancy. Diabetes. 2002;51(7):2207–13.
9. Sumathy V, Rajatharangini T, Padmanaban S. Association of elevated serum ferritin levels in mid pregnancy and the risk of gestational diabetes mellitus. Int J Clin Obstet Gynaecol. 2018;2(6):18–21.
10. Galal M, Salah M. Correlation between frst trimester pregnancy serum ferritin and risk of gestational diabetes in this pregnancy. Al Azharassiut Med J. 2015;13(2):3.
11. Poonguzhalai S,  Kalyanikutty  KP.  The  relationship between   serum   ferritin   and   gestational   diabetes mellitus A cross sectional study. IJOG. 2019;6:342-5.
12. Rawal S, Hinkle SN, Bao W, Zhu Y, Grewal J, Albert PS, et  al.  A  longitudinal  study  of  iron  status  during pregnancy and the risk of gestational diabetes: findings from  a  prospective,  multiracial  cohort.  Diabetologia. 2017;60(2):249-57.
13. Soheilykhah S,  Mojibian  M,  Jannati  Moghadam  M. Serum  ferritin  concentration  in  early  pregnancy  and risk of subsequent development of gestational diabetes: A  prospective  study.  Int  J  Reprod  Biomed.  2017;15(3):155-60.
14. Bowers KA, Olsen SF, Bao W, Halldorsson TI, StrømM, Zhang  C.  Plasma  Concentrations  of  Ferritin  in Early   Pregnancy   Are   Associated   with   Risk   of Gestational Diabetes Mellitus in Women in the Danish National Birth Cohort. J Nutr. 2016;146(9):1756-61.
15. Goldenberg RL, Tamura T, DuBard M, Johnston KE, Copper RL, Neggers Y. Plasma ferritin and pregnancy outcome. Am J Obstet Gynecol 1996;175:1356-9.
16. Scholl TO. High third-trimester ferritin concentration: association with  very preterm delivery, infection, and maternal  nutritional  status.  Obstet  Gynecol.  1998;92:161-6.
17. Raman L, Pawashe AB, Yasodhara P. Hyperferritinemiain pregnancy-induced  hypertension an eclampsia. J Postgrad Med. 1992;38:65-7.
18. Prasad DKV, Sheela P, Kumar AN, Kumar NL, Deedi MK, Madhulatha D. Iron level increase in serum from gestational diabetes mellitus mother in coastal area of Andra Pradesh: prospective study. J Diab Metab. 2013;23:32-8.
19. Lao TT,  Chan  PL,  Tam  KF.  Gestational  diabetes mellitus in the last trimester: a feature of maternal iron excess. Diab Med. 2001;18:218-23.
20. Johnston KE, Cliver SP, Hickey CA. Serum ferritin-a predictor of early spontaneous preterm delivery. Obstet Gynecol. 1996;87:360-5.
21. Islam N,    Chowdhury    SB.    Serum    ferritin    and Gestational  diabetes  mellitus;  A  case  control  study. Ibrahim Card Med J. 2011;1(2):15-9
22. Das CC, Sreekala KN, Geetha N. Serum ferritin in gestational diabetes. J Med Sci Clin Res. 2017;5:26814–9.
23. Cheng Y, Tingting L, Mulan H, et al. The association of elevated serum ferritin concentration in early pregnancy with gestational diabetes mellitus: a prospective observational study. Eur J Clin Nutr. 2020;74:741–8.