Criteria for diagnosing Gestational Diabetes
The Diabetes in Pregnancy Study group India (DIPSI) is reporting practice guidelines for GDM in the Indian environment. Due to high prevalence, screening is essential for all Indian pregnant women. DIPSI recommends that as a pregnant woman walks into the antenatal clinic in the fasting state, she has to be given a 75g oral glucose load and at 2 hrs a venous blood sample is collected for estimating plasma glucose. Screening is recommended between 24 and 28 weeks of gestation and the diagnostic criteria of ADA are applicable.
To standardize the diagnosis of GDM, the World Health Organisation (WHO) proposed using a 2 hour 75 gm OGTT with a threshold plasma glucose concentration of greater than 140 mg/dl at 2 hour.
With 75 gm OGTT (WHO criteria);
|In Pregnancy Outside Pregnancy|
|2 hr ≥ 200 mg/dl Diabetes Diabetes|
|2 hr ≥ 140 mg/dl GDM IGT|
|2 hr ≥ 120 mg/dl DGGT* —|
*- Decreased Gestational glucose tolerance
ADA/IADPSG revised recommendations for diagnosing GDM
Recommendations in 2011 for diagnosis of GDM were developed by the American Diabetes Association and the International Association of Diabetes and Pregnancy Study Groups (IADPSG). These recommended that patients at increased risk for type 2 diabetes be screened for diabetes using standard diagnostic criteria at their first antenatal visit.
Such high-risk individuals have glucose levels that, although not meeting criteria for diabetes, are nevertheless too high to be considered normal. These patients are defined as having impaired fasting glucose (IFG; fasting plasma glucose levels of 100 mg/dL to 125 mg/dL), or impaired glucose tolerance (IGT; 2-hour OGTT values of 140 mg/dL to 199 mg/dL). Individuals with an HbA1c of 5.7% to 6.4% are also considered at increased risk.
In these patients, confirmed fasting glucose levels of =126 mg/dL or random glucose levels greater than and equal to 200 mg/dL are also diagnostic of diabetes. The ADA and the IADPSG recommended that such high-risk women with diabetes diagnosed on the basis of standard diagnostic criteria receive a diagnosis of overt rather than gestational diabetes.
Women at high risk of GDM (personal history of GDM or polycystic ovarian syndrome, glycosuria, family history of type 2 diabetes, severe obesity, macrosomia of previous child) should also undergo glucose tolerance testing at the first antenatal visit, if possible, or soon thereafter.
At 24 to 28 weeks’ gestation, all women not known to have diabetes (including high-risk women if the initial testing was normal) should undergo screening with glucose tolerance testing. Either one-step or two-step screening methods may be used.
- Perform a 75-gram OGTT, with plasma glucose measurement fasting and at 1 and 2 hours, at 24 to 28 weeks of gestation in women not previously diagnosed with overt diabetes.
- The OGTT should be performed in the morning after an overnight fast of at least 8 hours.
- The diagnosis of GDM is made when any one of the following plasma glucose values are exceeded:
Fasting =92 mg/dL
1 hour =180 mg/dL
2 hours =153 mg/dL
Two-step screening method (recommended by the National Institutes of Health [NIH]):
1-hour 50-gram oral glucose tolerance test (OGTT): glucose >130 or >140 mg/dL at 1 hour is a positive screening test for GDM. This must be followed up with a 3-hour OGTT. This test is performed when the patient is fasting. Two or more plasma glucose levels at or above the following thresholds establish diagnosis.
3- hour 100-gram oral glucose tolerance test for screening in pregnancy
Source: American Diabetes Association. Standards of medical care in diabetes – 2014. Diabetes Care. 2014;37(suppl 1):S14-S80.
Levels of plasma glucose after the following tests indicate hyperglycaemia in pregnant women:
- Fasting glucose: =126 mg/dL confirmed on repeat testing. This diagnostic is usually used outside of pregnancy but may be useful in patients with signs or symptoms of hyperglycaemia.
- Random glucose level: =200 mg/dL confirmed on repeat testing, is diagnostic of diabetes. This is usually used outside of pregnancy but may be useful in patients with signs or symptoms of hyperglycaemia.
ACOG recommends a 2-step approach that involves an initial 1-hr, 50-g screening test and, for women who met or exceeded a threshold of 135 or 140 mg/dL, a 3-hour diagnostic OGTT using a 100-g load. For the 3-hour OGTT, two or more of the threshold values (ie, either the Carpenter and Coustan criteria or the plasma levels established by the National Diabetes Data Group) must be met to diagnose gestational diabetes.
Dr. Rajiv Kovil
Consultant Diabetologist, Dr. Kovil’s Diabetes Care Centre
Dr. Rajiv Kovil is a Consultant Diabetologist at Dr. Kovil’s Diabetes Care Centre, the first Preventive Diabetes Centre & Diabetic Foot Clinic in Mumbai, KLS Memorial Hospital and Holy Spirit Hospital among others. He is a founder member of United Diabetes Forum, a forum of practising diabetologists in India. He has also written various articles on diabetes for medical journals such as Asian Journal of Diabetology and Medical Image. His Preventive Diabetes Centre & Diabetic Foot Clinic is an initiative to provide preventive diabetic measures as well as to function as a specialized Foot Clinic for diabetic patients not only in terms of equipment but more importantly in terms of expertise.
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- All you need to know about Gestational Diabetes
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- Causes and symptoms of Diabetes (Types 1&2)
- Types of diabetes in India
- Are you at risk for diabetes?
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