Diabetes Mellitus:- Part 4 – Gestational Diabetes Mellitus, Oral glucose tolerance test, (OGTT)

Gestational Diabetes Mellitus

What Samples are needed for patients with Gestational Diabetes Mellitus?

1. The patient is advised to come to the laboratory in a fasting state, where, after taking a fasting blood sample, the patient is given 75 grams of glucose.
2. It is better to give glucose in 7-Up, which will be well tolerated.
3. Collect fasting blood and then collect blood samples at 30, 60, 90, and 120 minutes.
4. Multiple samples are taken at half-hour intervals along with the urine sample.
5. In pregnant women, collect blood at 60, 120, and 180 minutes after glucose administration.
6. Sometimes, the sample is taken at 1, 2, 3, and up to 4 hours.

What are the Indications for the diagnosis of Gestational Diabetes Mellitus?

1. To confirm the diagnosis of gestational diabetes.
2. It is used to diagnose Diabetes mellitus.
3. It is also used to evaluate hypoglycemia.
4. Patient with family H/o diabetes.
5. Patients with obesity.
6. Patients with H/O recurrent infection.
7. Patients with H/O delayed wound healing.
8. Ladies with H/O stillbirths or delivering obese babies.
9. Patients with H/O random glycosuria or hyperglycemia during pregnancy or after myocardial infarction, surgery, or stress.

What are the Precautions for Gestational Diabetes Mellitus?

1. Advise the patient to consume more than 150 grams of carbohydrates in their diet over the last 3 days before the test.
2. Stop these drugs at least 3 days before the test, such as hormones, contraceptives, steroids, salicylates, and anti-inflammatory medications.
3. Stop diuretics, hypoglycemic agents, antihypertensive drugs, and anticonvulsants.
4. Stress can increase glucose levels.
5. If the patient does not tolerate the glucose and vomits, that may give a false result.
6. Avoid glucose tolerance tests in the following conditions:
   1. If there is persistent fasting hyperglycemia >140 mg/dL (>7.8 mmol/L).
   2. In the event of a normal fasting glucose level.
   3. Patient with known diabetes mellitus.
7. In the case of two hours, glucose >200 mg/dL (>11.1 mmol/L).

What are the recommendations for pregnant ladies?

1. It is recommended that screening be done on all pregnant women between 24  and 28 weeks of gestation.
2. This should be advised for women aged 25 years or older.
3. Also advised before the age of 25 years if the woman is obese or there is a family history of DM.

What is the definition of Gestational Diabetes Mellitus (GDM)?

1. Gestational diabetes mellitus is defined as any degree of glucose intolerance that is seen during pregnancy.
   1. Usually seen around 24 weeks of gestation.
2. Gestational Diabetes Mellitus (GDM) is also defined as hyperglycemia that develops for the first time during pregnancy. This condition is observed in approximately 4% of pregnant women.

How will you discuss the pathophysiology of Gestational Diabetes Mellitus (GDM)?

1. A normal pregnancy is associated with increased insulin resistance, especially in the late second and third trimesters.
2. GDM, in which hormones produced by the placenta prevent the body from utilizing insulin. This will lead to an increase in blood glucose levels.
3. This will occur in pregnant women who cannot maintain a sufficient insulin level.
4. The risk factors are:
   1. Family history of a first-degree relative with diabetes mellitus.
   2. In obese ladies.
   3. In the case of late maternal age, it typically occurs after the age of 40.
   4. If there is glycosuria.
   5. Bad previous delivery history, such as stillbirth and macrosomia.
5. Screening should be performed between 24 to 28 weeks of gestation.
6. 3% to 8% of pregnant women have gestational diabetes.

What are the complications of gestational diabetes mellitus?

5. The detection of early GDM will reduce the risk of prenatal fatal outcomes, such as:
   1. Excessive fetal growth.
   2. Birth trauma.
   3. Fetal morbidity.

How will you do screening for gestational diabetes mellitus(GDM) during pregnancy?

1. It can be assessed by a one-hour blood glucose level if it is greater than 140 mg/dL.  Then, advise OGTT for three hours.
2. The O’Sullivan test is a one-hour glucose tolerance test administered after the ingestion of 50 grams of oral glucose.
3. Screening for GDM advises OGTT with 50 grams of glucose.
4. Check the one-hour glucose level, also known as the O’Sullivan test.
5. Screening should be done between 24 to 28 weeks of gestation.
6. If one one-hour sample is >140 mg/dL, then taking a 3-hour 100-gram glucose tolerance test (OGTT) is necessary.
   1. Normal pregnancy is associated with increased insulin resistance, especially in the second and third trimesters.

How will you screen for gestational diabetes mellitus during the postpartum period?

1. If the results are abnormal during pregnancy, then take the OGTT postpartum.
2. If postpartum OGTT is normal, then label diabetes mellitus during pregnancy.
   1. Check blood glucose on every visit because of the increased risk of diabetes mellitus, which is 30% during the next 5 to 10 years.
3. If the postpartum OGTT is abnormal, label these patients as having Impaired glucose tolerance (IGT) or Impaired fasting glucose (IFG), which can occur in ∼approximately 5% to 10% of cases.
   1. Another possibility is a clear-cut case of diabetes mellitus, which can occur in 10% of cases.
   2. The rest of the ladies are normal and may develop diabetes mellitus in the next 5 to 10 years.

What are the risk factors for Gestational Diabetes Mellitus?

5. A family history of diabetes in first-degree relatives.
6. Obesity.
7. Advanced maternal age.
8. Glycosuria.
9. A selected bad outcome in the last pregnancy, like stillbirth or macrosomia.

What is the modified criteria for the diagnosis of Gestational Diabetes Mellitus (GDM)?

1. Low-risk patients are:
   1. Below the age of 25 years.
   2. Normal weight before the pregnancy.
   3. The ethnic group with a low incidence of GDM.
   4. No known first-degree relative with diabetes mellitus.
   5. No history of poor obstetric outcomes.
   6.  There is no history of abnormal glucose tolerance.
2. Average-risk patients are:
   1. All those patients fall between low and high-risk patients.
   2. They should be tested between 24 to 28 weeks of gestation.
3. High-risk patients are:
   1. Marked obesity.
   2. Glycosuria.
   3. History of GDM.
   4. Strong family history of diabetes mellitus.

What is the importance of Gestational diabetes mellitus (GDM)?

1. OGTT is not recommended to diagnose the complications of Diabetes mellitus.
2. Its use is also discouraged for fasting hypoglycemia.
3. The OGTT is not recommended as a screening test in non-pregnant women and children.
4. For a pregnant lady, 50 g of glucose is recommended for screening.
5. The serum glucose level of >150 mg/dL at 1 hour is considered for further testing.
6. Insulin responds rapidly to oral glucose, with peaks at 30 and 60 minutes.
7. Glucose levels return to normal within 3 hours.
8. Glucose will not appear in the urine in a normal pattern.

What is the procedure for the Oral glucose tolerance test (OGTT)?

1. Record patient weight.
2. The pediatric dose for glucose amount is based on their weight, calculated as 1.75 g/Kg, and should not exceed a total of 75 grams.
3. Pregnant ladies can be given 100 grams.
   1. Can perform the test on pregnant ladies with 50 grams of glucose.
   2. Non-pregnant ladies can be given 75 grams.
4. Take the fasting blood for fasting glucose levels.
5. Give glucose (Glaxo ‘s-D) 75 to 100 grams in 5 minutes.
6. Pregnant ladies can perform the test with 50 grams of glucose.
7. Take the blood sample at 30, 60, 90, 120, and 180 minutes (some books recommend 30 minutes, 1 hour, 2 hours, and 3 hours) after glucose intake.
8. To check for hypoglycemia, advise taking 4 4-hour samples.
9. Also, take the urine sample with every blood sample.

How will you record the collection of blood and urine during OGTT?

What are the Normal values of glucose?

Source 1

1. NORMAL WHEN
   1. Fasting glucose = < 110 mg/dl.
   2. Random glucose = < 140 mg/dl.
2. Child fasting = <130 mg/dl.
   • at 120 min = < 140 mg/dl.
   • Impaired glucose tolerance in children:
   • Fasting = <140 mg/dl.
   • 120 min = >140 mg/dl.

Adult non-pregnant OGTT result:

• Fasting = 79 to 105 mg/dl.
• 30 min = 110 to 179 mg/dl
• 60 min = 120 to 170 mg/dl
• 90 min = 100 to 140 mg/dl
• 120 min = 70 to 120 mg/dl
• All urine samples are negative.
• >60 years  fasting = 70 to 115 mg/dL

Gestational diabetes normal one hour = <140 mg/dL

Diabetes Mellitus when:

1. Fasting glucose = 126 mg/dl or above
2. Postprandial glucose = 200 mg/dl or above
3. Random glucose more than 200 mg/dl with H/o polyuria, polydipsia, ketonuria, and weight loss.

IMPAIRED GLUCOSE when:

1. Impaired fasting Glucose = 110 to <126 mg/dl
2. Impaired glucose tolerance = 140 to <200 mg/dl

Source 2

Normal values of OGTT in Adults:

What are the values of the OGTT in gestational diabetes mellitus (GDM)?

• At least two values of  OGTT must exceed the following values for GDM:
  • Fasting = >95 mg/dL.
  • 1 hour => 180 mg/dL
  • 2 hour => 155 mg/dL
  • 3 hour => 140 mg/dL
• High glucose level persists throughout the test.
• Another source gives the following values:

At least two values must meet or exceed the following  values for GDM based on the oral glucose tolerance test:

Gestational diabetes mellitus (GDM)

How would you summarize the work-up for gestational diabetes mellitus?

Screening workup :

1. Perform the work-up of all pregnant ladies during the 24 to 28 weeks of gestation over the age of ≥25 years.
2. Also, check the ladies, even if they are <25 years of age, for the risk factor.
3. Perform a mini OGTT with 50 grams of glucose without any relation to the food.
   1. Measure the glucose level for one hour.
   2. If this glucose level is ≥140 mg/dL, then perform the complete OGTT.

How will you perform a workup for Gestational diabetes mellitus?

1. Perform OGTT after 8 to 14 hours of fasting.
2. Take fasting glucose orally.
3. Give 100 grams of glucose.
4. Measure blood glucose hourly for 3 hours.
5. At least two values must exceed all values.
6. If results are expected in a clinically suspected case, then repeat OGTT in the 3rd trimester.

Criteria for the positive 100-gram (OGTT) in pregnant women (Gestational diabetes):

 What is the treatment of Gestational diabetes mellitus?

1. The basic need is to control the diet.
2. The second critical need is physical activity.
3. Can have a daily glucose level and administer the medication accordingly.
4. For management of GDM during pregnancy, keep fasting blood glucose level 60 to 110 mg/dL and postprandial level <150 mg/dL.
5. It is needed to measure the 24-hour urine estriol level for fetal viability.
6. Also, check the amniotic fluid for fetal pulmonary maturity.
7. During labor, maintain a blood glucose level between 80 and 100 mg/dL, as there may be marked insulin sensitivity during the immediate postpartum period.
8. Evaluate the patient after 6 weeks of postpartum.

What are the criteria For Adequate Treatment of gestational diabetes mellitus?

1. The fasting level should be around 95 mg/dL or less.
2. The postprandial, 1-hour level is around 140 mg/dL or less.
3. The Postprandial 2-hour level is 120 mg/d or less.

• Gestational diabetes mellitus goes away after pregnancy.
• In ladies with GDM, there is a 2 in 3 chance of developing GDM in other pregnancies.
  • For more information, please see other topics on Diabetes mellitus.

Questions and answers: