The validity of single step test (DIPSI) for screening for GDM in all trimesters of pregnancy

Purpose: To evaluate the validity of DIPSI, (Diabetes and Pregnancy Study Group India) a single step test, as a screening tool for GDM and to find out the incidence and onset of GDM with respect to period of gestation. Materials and Methods: One year prospective study was conducted on 300 antenatal women in all three trimesters with DIPSI – Single step test. DIPSI positive patients underwent diagnostic OGTT, by 75 gm glucose. Patients were diagnosed as GDM by WHO Criteria (1999). Results: DIPSI had sensitivity of 100%, specificity of 94.6%. Of the 300 patients subjected to the study, overall incidence of GDM was 25.3% and 0.7% were diagnosed with overt diabetes. During the first trimester 4% had GDM whereas 0.7% had overt diabetes. During the second and third trimester 12.5% and 15.3 % of patients were newly diagnosed with GDM respectively. Conclusion: This evidence not only validates DIPSI as simple and efficient screening test but also emphasizes the importance of subjecting all the pregnant women in all 3 trimesters to test for screening for GDM. And therefore this test should become part of the routine antenatal investigations.


Introduction
Gestational diabetes mellitus (GDM) is defined as carbohydrate intolerance with onset or recognition during pregnancy. Women with GDM are at increased risk of future diabetes predominantly type 2 diabetes mellitus (DM) and is also associated with increased risk of fetal morbidity and mortality. The prevalence of GDM in India varies from 3.8 to 21% in different parts of the country, depending on geographical locations and diagnostic methods used [1][2][3]. GDM affects up to 15% of pregnant women worldwide, India alone has an estimated 4 million women with GDM.
Pregnancy is considered to be a diabetogenic state characterized by exaggerated rate and amount of insulin release, associated with decreased sensitivity to insulin at cellular levels. Hormones like estrogen, progesterone, human placental lactogen, cortisol and growth hormone are anti insulinogenic. These hormones increase in mid pregnancy period and cause abnormal glucose tolerance There are lot of controversies regarding many aspects of GDM. Important being type of screening, whether universal or selective, which screening test and diagnostic test to follow, about ideal cut off levels, whether to treat or not, how to treat best so on and so forth. Unfortunately there is no universally accepted gold standard for diagnosis of GDM and the commonly utilized methods and threshold criteria for diagnosis of GDM in themselves give different results. In the usual screening protocol recommended by ADA, which is universally followed, all pregnant patients are screened with 50gm GCT. If the patient is test screen positive GCT >140mg/dl the patient is asked to come back for 3hr 100gm GTT.
According to study done by Seshaiah et al 23% of screen positive women do not return for the confirmatory 3 hr. OGTT [4]. This phenomenon of no show occurs because the women have to come to antenatal clinic on two occasions for the blood test by

Original Research Article
Obsgyne Review: Journal of Obstetrics and Gynecology Available online at: www.medresearch.in 35 | P a g e this two step protocol. Also the requirement of a number of blood samples for the diagnosis of GDM is not feasible and conducive especially in the Indian context. Hence for Universal screening, Seshaiah et al suggested a single step 75gm GCT (DIPSI-Diabetes In Pregnancy Study Group India) instead of two step procedure. This method serves as both one step screening and diagnostic procedure and is easy to perform besides being economical [5].
Insulin is detectable in fetal pancreas as early as nine weeks after Conception. An increase in beta cell mass and insulin secretion in the fetus occurs by the 16th week of gestation, in response to maternal hyperglycemia. The priming of the fetal beta cells may account for the persistence of fetal hyper insulinaemia throughout pregnancy and risk of accelerated fetal growth even when the mother enjoys good metabolic control in later pregnancy. This necessitates performing the test procedures to diagnose GDM in the first trimester itself. Further, early detection and care, results in a better fetal outcome.
There are only a few studies done on screening for GDM in all three trimesters of pregnancy in India, therefore the following study is undertaken to screen for GDM in pregnancy in all trimesters in the pregnant women attending antenatal clinic in Vijay Marie Hospital & Educational Society using single step procedure (DIPSI). This study also helps to determine the incidence of GDM with respect to different period of gestation. This study screens for GDM in all three trimesters of pregnancy thus helps to find, missed out cases in 1 st and 3 rd trimester if usual screening test done at 24-28wks. By using a single step method in the first trimester itself we will be able to pick up the cases who have pre gestational as well as early onset gestational diabetes mellitus. The test also is less time consuming and convenient for the patient.

Materials and Methods
One year descriptive/prospective study done from June 2014 to June 2015 on 300 pregnant women who were registered in 1 st trimester for antenatal checkup at Vijay Marie Hospital from June -September 2014, they were followed up to 9 months. All pregnant women in 1 st trimester, irrespective of maternal age and gravidity, presence or absence of clinical or historic risk factors of GDM are included in the study. Known diabetic patients before pregnancy (pre gestational Diabetes) were excluded. The selected patients were briefed about the nature of the study, details of the test and a written informed consent was obtained. Demographic data like age and obstetric history along with relevant history was recorded on predesigned and pretested proforma. A detailed history is taken, general physical examination including BMI, systemic examination and obstetric examination was done. Body Mass Index was calculated based on formula -BMI = weight (kg)/Height (m2). BMI in the range of <18.5kg/m2 were considered as underweight,18.5-24.9kg/m2 were considered as normal, 25-29.9kg/m2 were considered as overweight, >30kg/m2 were considered as Obese.
The Pregnant women in first trimester who were selected in the study were given 75 grams of glucose dissolved in 300 ml of water and asked to drink it over a five minute period, irrespective of time of the day and her last meal. After 2 hours of ingestion of glucose, venous blood is drawn. The plasma glucose is estimated by glucose oxidation and per oxidation (GOD-POD) method. If plasma glucose value is ≥ 140mg/dl, the screening is considered as positive. If test results are negative they undergo a repeat test at 24-28wks and if found negative test is repeated at 32-34wks gestational age. Patients with glucose value of 200mg/dl or more are directly diagnosed as GDM without the need for OGTT. The DIPSI positive patients underwent a diagnostic OGTT, by 75gm of glucose. Three days prior to OGTT test, patients are asked to take normal unrestricted diet. After overnight fasting of 8-14 hours, a fasting blood sample was drawn; following which 75gm of glucose dissolved in 300-400ml water is given orally. Thereafter venous glucose plasma levels are assessed after 2hours. Patients were diagnosed as GDM by WHO Criteria (1999) [FBS >126mg/dl, post 75gm glucose load 2hr PG >140mg/dl. Any one value must be positive.]

Results
After collecting data, statistical analysis was done by using Descriptive statistics -Mean, Standard deviation, and the inferential statistics -chi square test and SPSS 17 th version of software. In the present study, majority (48.7%) had age between 20 to 24 years followed by 25 to 29 years (31.7%), 30 to34 years (9.3%), 15 to 19 years (9%) and 35-40 years (1.3%). Over all Mean Age was 24.07 ± 3.77 years, Range being 17-35years. 157 (52.3%) women had BMI in the range

Original Research Article
Obsgyne Review: Journal of Obstetrics and Gynecology Available online at: www.medresearch.in 36 | P a g e of 25-29.9 Kg/m2, followed by 117 (39%) in range of 18.5-24.9 kg/m2 and 26 (8.7%) women >30kg/m2. Overall Mean BMI was 25.5 ± 2.74 kg/m2 with range being 20-32 kg/m2. According to DIPSI incidence of GDM in 1 st trimester is 4.6% and overt diabetes is 0.7%. During the 2 nd trimester 23 patients lost to follow up and 16 patients were screened as GDM positive during 1 st trimester. Of the remaining 261, 39(14.9%) patients were newly screened as GDM positive. During the 3 rd trimester, 27 more patients lost to follow up. 16 patients were screened as GDM positive in 1 st trimester and 39 patients were screened as GDM positive during second trimester. Of the remaining 195 patients, 35 (17.9%) patients were newly screened as GDM positive. According to WHO (1999) criteria in present study, 12(4%) were diagnosed to have GDM in 1 st trimester, 2(0.7%) to have overt diabetes. In 2 nd trimester 23 lost follow up, out of remaining 263 women, 33 (12.5%) were newly diagnosed to have GDM, in 3 rd trimester 27 lost for follow up 31(15.3%) were newly diagnosed as GDM.   There was no positive correlation with increasing AGE and increase in incidence of GDM in all three trimesters P value > 0.05.

Original Research Article
Obsgyne Review: Journal of Obstetrics and Gynecology Available online at: www.medresearch.in 37 | P a g e There was positive correlation between increasing BMI and increase in incidence of GDM in all three trimesters. (p< 0.05). Out of 300 women subjected to study total of 26 women were having BMI> 30 kg/m2, 62 were having family history of diabetes, 9 were having previous pregnancy with GDM, 4 were having previous history of IUFD/neonatal death, 2 were having macrosomia. Many were having more than one risk factor. There was correlation between risk factors and increase in incidence of GDM (p value <0.001) and significant correlation with risk factors like obesity, GDM in previous pregnancy, family history of GDM (p <0.001). In present study 54 (69.2%) GDM patients had risk factors, 24 (30.8%) GDM patients had no risk factors. Hence universal screening is recommended.

Discussion
Gestational diabetes mellitus (GDM) is defined as carbohydrate intolerance with onset or recognition during pregnancy. Women with GDM are at increased risk of future diabetes predominantly type 2 diabetes mellitus (DM) and is also associated with increased risk of fetal morbidity and mortality. Ferrara et al showed the incidence at 7.5% in Asians, 5.6% in Hispanics, 4%, African American. 6  all the three trimesters (p>0.050), In clinical practice, maternal age of ≥25 years should be adopted instead of ≥35 years or 40 years as a risk factor for the development of GDM. 8 In the UK, Sebire studied the effects of maternal obesity on pregnancy outcomes in a London cohort of 287, 213 women. Since then, similar reports have been published from Wales and Scotland. 9 Risk factors for GDM include a high BMI, excessive weight gain or low physical activity during pregnancy, high dietary intake of polyunsaturated fats, glucose intolerance or the birth of a large baby in previous pregnancy, and a family history of diabetes. The Present Study showed a significant association between GDM (p < 0.050).

Conclusion
The DIPSI test used in the study for screening for GDM proved to be simple, less cumbersome, cost effective and easily acceptable to the patients. Screening for GDM in all three trimesters is equally important. 30.8% of patients with no risk factors had GDM. Hence universal screening is recommended.
The present study also showed association of increasing BMI with increasing incidence of GDM, although it did not show positive correlation of increasing age with the incidence of GDM. This evidence is enough to evaluate the efficacy of subjecting all the pregnant patients to test for screening for GDM in all three trimesters and this test should become the part of routine antenatal investigations.