Diabetes In Pregnancy - Study Questions & Answers

A 30 year old woman with diabetes mellitus presents to her physician  at 19 weeks’ gestation. She is obese and did not realize that she was pregnant until recently. She also has not been “watching her sugar” lately, but is now motivated to improve her regimen. 

A dilated ophthalmologic examination shows no retinopathy. An ECG is normal.
Urinalysis is negative for proteinuria. 

Laboratory studies show:

• HbA1c : 10.8%

• Glucose : 22 mg/dl

• TSH : 1.0 microU/ml

• Free thyroxine: 1.7 ng/dL

• Creatinine: 1.1 mg/dL.

Question: Which of the following condition has the same risk of developing in diabetics as the general population.

a. Asymptomatic bacteriuria

b. Preeclampsia

c. Congenital adrenal hyperplasia

d. PPH after delivery

e. Shoulder dystocia

Answer: c. Congenital adrenal hyperplasia

Question:  A 30-yrs-old G3P2 patient visits an antenatal clinic at 20 weeks. She reveals during history that her first baby was 4.6 kg delivered by cesarean section, second baby was 4,8 kg delivered by c/section. Gynaecologists suspects gestational diabetes and orders a Glucose tolerance test. The blood sugar levels after 50 gms of oral glucose are 206 mg/dl and the patient is thus confirmed as a case of gestational diabetes. 

All of the following are known complications of this condition except:

a. Susceptibility for infection

b. Fetal hyperglycemia

c. Congenital malformations in fetus

d. Neonatal hypoglycemia

Answer: c. Congenital malformations in fetus

Question: A 30-year-old G3P2 obese woman at 26 weeks’ gestation with no significant past medical history states that diabetes runs in her family. Her other pregnancies were uncomplicated. 

The results of a 3-hour glucose tolerance test show the following glucose levels:

• 0 (fasting): 90 mg/dL 

• 1 hour: 195 mg/dL

• 2 hours: 155 mg/dL 

• 3 hours: 145 mg/dL

As a result she is diagnosed with gestational diabetes. She is counselled to start diet modification and exercise to control her sugar levels. 

3 weeks after her diagnosis she presents again and now her tests are: 

• Fasting : 95 mg/dl

•1 hour post prandial : 185 mg/dl

What is the best management?

a. Continue diet modification

b. Start insulin

c. Repeat Glucose tolerance test.

d. Start Metformin

Answer: b. Start insulin

Question: Fasting Blood sugar should be maintained in a pregnant diabetic female as:

a. 70 – 100 mg%

b. 100 – 130 mg%

c. 130 – 160 mg%

d. 160 – 190 mg%

Answer: a. 70 – 100 mg%

Discussion:

Diabetes In Pregnancy: Diabetes in pregnancy can be

1. Gestational Diabetes

• Normoglycemic female develops diabetes in pregnancy due to insulin resistance (insulin resistance in pregnancy is maximum at 24-28 weeks and is mainly due to the effect of hormone Human placental lactogen).

• These females will thus have high sugar levels at or after approx. 24 weeks.

• In diabetic patients high blood sugar levels lead to formation of free radicals which in turn lead to fetal malformations, now in gestational diabetic patients free radicals will be formed approx. after 24 weeks (i.e when blood sugar levels will rise)

• By 24 weeks almost the organogenesis is complete in the fetus so it does not lead to congenital malformation in fetus.

2. Over Diabetes

• Hyperglycemic female becomes pregnant.

• Switch them from oral hypoglycemic to insulin as oral hypoglyincemic can cross the placenta.

• These females have high sugar levels from Day 1 of pregnancy so free radicals are formed from Day 1 and thus it can lead to congenital malformations in fetus.

In Overt diabetic patients –the test which can predict the chances of congenital malformations in the fetus is Hb A1C. (HbA1c <8.5 gm% risk of malformation is 3.4%, HbA1c > 9.5 gm% risk of malformation is 22%).

Diagnostic Criteria for Diabetes during Pregnancy

According to American Diabetes association the criteria for diagnosis of overt diabetes during pregnancy is:

a. Random plasma glucose >200 mg/dl

b. Fasting blood glucose >125 mg/dl

c. Two or more abnormal values on 100 gm oral glucose tolerance test during pregnancy.

Complications of Diabetes

Maternal

• Infection

• Pregnancy induced hypertensio n

• Polyhydramnios

• Preterm labor

• 35-50% chances of developing diabetes later in life

Fetal

• Hyperglycemia

• Macrosomia

• Shoulder dystocia

• Miscarriage, intrauterine death, still birth

Neonatal

• Hypoglycemia

• Hypocalcemia

• Hypomagnesemia

• Hypokalemia

• Hyperviscosity syndrome (hyperbilirubinemia and polycythemia)

• Prematurity/Respiratory distress syndrome

Screening for Diabetes During Pregnancy

Glucose Challenges Test:

• Performed by orally administering 50g of glucose and measuring venous plasma glucose 1 hour later irrespective of previous meal.

• Interpretation of result:

– Plasma glucose: Interpretation

– 140 mg/dl: Further testing by GTT required

– 140 mg/dl: Further testing not required.

– 200 mg/dl: No further testing required as values > 200 mg/dl confirm the diagnosis of gestational diabetes.

• Time for screening: Between 24 and 30 weeks of gestation (patients at high risk should be screened between 18-22 weeks and if initial screenings is negative it can be repeated between 26 and 30 weeks).Ideally it should be performed in all pregnant females but all those who have average/high risk for diabetes should be screened.

Diagnostic Test-Glucose Tolerance Test:

• Patients with abnormal screening test are followed by a 3 hour glucose tolerance test (GTT)

• The test is performed with 100gm of glucose. 

Upper limit of normal for the 3 hour glucose tolerance test during pregnancy:

– Fasting: 95 mg/dl

– One hour: 180 mg/dl

– Two hour: 155 mg/dl

– Three hour: 140 mg/dl

• If two or more of these values are abnormal: Gestational diabetes is confirmed.

• If one value is abnormal: Increased risk of complications like macrosomia and preeclampsia - eclampsia. (Though gestational diabetes is not present)

• WHO recommends use of glucose of 75 g GTT and only two samples to be withdrawn viz: The fasting and the 2 hour value.