Although diabetes mellitus during pregnancy (DIP) causes hyperglycemia in pregnancy (HIP), it is gestational diabetes mellitus (GDM) that remains the major cause of HIP. DIP, either antedating or detected during pregnancy, is the more hazardous form of HIP, producing severe hyperglycemia early in pregnancy, which persists postpartum; on the other hand, GDM causes mild hyperglycemia late in pregnancy, which usually disappears after delivery. As normal pregnancy advances, it causes insulin resistance.
The resulting hyperglycemia is compensated for in healthy women by pancreatic beta-cell hyperplasia, which can meet the additional metabolic demands. However, in GDM, there is inadequate compensation due to multiple genetic and environmental factors, causing hyperglycemia 
. Though GDM is associated with maternal and fetal complications in index pregnancy, additional problems exist. After delivery, a woman with GDM is ten times more likely to develop type 2 diabetes mellitus (T2DM) than a woman without GDM 
. Intense screening, follow-up, and preventive measures for women with GDM after delivery can help mitigate impending T2DM in an individual patient and potentially in an entire population, epidemiologically 
. Due to the current epidemic of T2DM worldwide, post-partum follow-up of women with GDM is crucial for all counties, especially countries with a high prevalence of diabetes mellitus (DM). Being one such country, India harbors the second-highest number of adults with T2DM globally, a number slated to increase by more than 75% in the next 25 years 
Therefore, all countries must align themselves to the latest research on every aspect of GDM, from screening to management and the critical long-term follow-up after delivery. The lack of a uniform global approach to GDM remains one major roadblock plaguing GDM and our prospects of turning the tide on the T2DM epidemic 
2. Challenges Caused by Diabetes Mellitus
Though T2DM has become an epidemic across the world , it is the seven countries of SEA (Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka) that bear the brunt, accounting for approximately a quarter of the global burden of diabetes and prediabetes . In 2019, 88 million adults with DM were living in SEA, with over half the adults (57%) being undiagnosed . If the current trends continue, 114 million Indians will be affected by 2045 , and India may overtake China as the DM capital of the world.
A recent study pooling 69 studies from 1,778,706 adults in India showed that between 1972 and 2019, the prevalence of T2DM increased in rural and urban India from 2.4% to 15% and from 3.3% to 19.0%, respectively . Since GDM parallels the prevalence of T2DM, any increase in diabetes mellitus prevalence changes the number of women affected with GDM. Thus, most GDM in Asia is higher than that in European countries, as T2DM prevalence is much higher in Asians. Recent epidemiological data show that T2DM affects much younger women, who develop HIP once they become pregnant. The mortality and morbidity of DM and GDM would continue unabated without urgent action and preventive programs. However, since women constitute half of any population, and GDM is a marker for T2DM, active postpartum follow-up can help contain the increasing prevalence of DM.
3. Further Progress in the Treatment of GDM in India
Due to the progress in GDM treatment globally, with the ease of access to knowledge, Indian health professionals have always been well aware of the overall health and economic benefits that accrue from identifying and treating GDM, both in the short term (perinatal complications) and the long time through postpartum lifestyle interventions to prevent or delay the onset of T2DM, obesity, and cardiovascular diseases, both in the mother and offspring. It was realized that the screening protocol in India had to be standardized by clearly defining (a) whom to test, (b) how to test, and (c) when to test.
3.1. Whom to Test? The Move from Selective to Universal Screening
In India, a technical assistance group (TAG) on DM within the Ministry of Health led to the development and publication of the GDM guidelines in 2014 by the government of India 
. These recommended moving towards universal rather than selective clinical screening for GDM, followed previously. Based on the data showing that Asians were 11 times more prone to GDM, FIGO, the Federation of Obstetric and Gynaecological Societies of India (FOGSI), and the Government of India recommended universal testing for all pregnant women. The experts within the country recognized that selective testing would translate into missed opportunities and that testing should be offered to all women irrespective of age, family history of DM, and previous obstetric history.
Thus, the concept that we must move from selective to universal screening was beginning to consolidate. However, more critically, a transition from awareness to practical initiatives was instituted.
3.2. How to Test? The DIPSI Test
The next big question was which universal screening test was practicable for all the pregnant women in India? Was it the 50-g GCT? The full 75-g OGTT? With 25 million births annually in India, any form of screening would place a significant burden on a poorly resourced health system. Therefore, any recommendation for testing women for HIP would need to be pragmatic, feasible, convenient, and cost-effective. Another problem in India was collecting a fasting glucose sample for multiple reasons. The cultural belief that pregnant women should not fast for long hours was a significant problem, insular to India. Furthermore, the drop-out rate became higher if the pregnant woman was asked to come again the next day (after the routine obstetric visit) for an OGTT.
One solution was proposed after a landmark study by Seshiah et al. claimed that a plasma glucose 2-h value after 75-g OGTT ≥ 140 mg/dL was comparable to the GCT and the 75-g OGTT used both fasting and the 2-h plasma glucose value 
. This test was essentially modified from the now obsolete WHO-1999 criteria for 75-g OGTT to diagnose GDM but was performed in a non-fasting state. This test was potentially helpful for many reasons: it was simple to perform, economical, did not need a fasting glucose sample, and compared favorably with more elaborate tests of glucose intolerance in pregnancy. The authors touted this test with an Albert Einstein quote, “Most complicated problems in the universe have a simple solution.” Thus, in 2006, the Diabetes in Pregnancy Study Group, India (DIPSI) decided that venous plasma glucose should be measured (despite a non-fasting state, irrespective of the last meal) 2 h after the 75-g glucose test. Its acronym better knew this test: the DIPSI test. Subsequent studies 
confirmed that the survey by Shah et al. correlated well with the WHO 1999 recommendations. It was similar but was performed in a non-fasting state; however, some studies did not agree with these findings 
3.3. National Guidelines for the Diagnosis and Management of Gestational Diabetes Mellitus, India
In 2014, the Maternal Health Division of the Ministry of Health and Family Welfare, Government of India (MOHFW) published the national guidelines for diagnosing and managing GDM in India 
. They recommended the DIPSI test at booking, and if it was negative, to repeat it between 24–28 weeks gestation for all pregnant women. A standardized glucometer was to be used, and it needed to be calibrated using a standard protocol. They updated their guidelines in 2018 
, using national and international studies. Experts studied the logistic limitations and stressed newer technical operative ideas. As in the first recommendations, testing a woman two times remained central to the updated guidelines 
. However, as outlined below, they stressed the proper use of operational procedures, using the glucometer for self-monitoring (SMBG) and oral hypoglycemic agents (OHA).
(A) Point of care using a glucometer: ideally, for the diagnosis of GDM, test results should be based on venous plasma samples, appropriately collected and transported quickly for testing to the laboratory, which professional laboratory bodies must accredit. However, this ideal situation is challenging to attain, especially in many primary care settings, particularly in PHCs in remote areas—where proper facilities for collection, transport, storage, or testing may not exist. In this situation, it was acceptable to use a plasma-calibrated hand-held glucometer with properly stored test strips to measure plasma glucose. Using a glucose meter in this situation may be more reliable than laboratory tests done on inadequately handled and poorly transported samples. Using a glucometer has made screening possible in many remote areas where it was not possible earlier. However, proper staff training was the key to success with a laboratory glucometer.
(B) Self-monitoring-blood-glucose (SMBG): glucometers were also used widely and effectively to monitor blood glucose once GDM had been diagnosed. Many women preferred a daily blood glucose check rather than a weekly/fortnightly fasting and postprandial check in the laboratory. Using a glucometer and testing herself often made the patient more involved in her treatment. Furthermore, she realized which foods to avoid, and she could inform clinicians about her glucose control.
(C) The use of oral hypoglycemics (OH): metformin has been approved for use in GDM after 20 weeks of gestation by the Central Drugs Standard Control Organization of India, which is the pharmaceutical watchdog, equivalent to the US Food and Drug Administration (FDA). The advantages of OH are as follows: it is easy to take, being an oral medication; it seldom causes hypoglycemia; it is more readily acceptable to the patient (compared to insulin), and it is much cheaper. It also limits the use of insulin to a select few women—those who cannot tolerate metformin or women in whom metformin fails to control the plasma glucose.