Diabetes mellitus in pregnancy: Gestational diabetes mellitus diagnostic criteria

Diagnosis of gestational diabetes mellitus is based on oral glucose tolerance test, which is usually done after 24 weeks of gestation. In most parts of the world the diagnostic criteria are based on either the 100 gram 3-hour test or the 75 gram 2-hour test. Many national bodies have created their own criteria based on local experience and their healthcare systems. The test is usually done when there is indication, which is the presence of risk for gestational diabetes mellitus. Risk assessment for gestational diabetes mellitus should be undertaken at the first antenatal visit. Pregnant women with no risk may not need to undergo the test. Some women with very high risk for gestational diabetes mellitus may need to take the test earlier than 24 weeks.

These are some different guidelines for diagnosis of gestational diabetes mellitus.

One abnormal value is sufficient for diagnosis

One abnormal value is sufficient for diagnosis
IADPSG=International Association of Diabetes and Pregnancy Study Groups

At least 2 abnormal values are needed to make diagnosis
ADA=American Diabetes Association

Positive screening indicates need for diagnostic test of 100g glucose load
For the diagnostic test, least 2 abnormal values are needed to make diagnosis
ACOG=American College of Obstetricians and Gynecologists

Positive screening indicates need for diagnostic test of 75g glucose load
For the diagnostic test, least 2 abnormal values are needed to make diagnosis

Diabetes mellitus in pregnancy: ultrasound work up during antenatal phase

-Example of ultrasound schedule-
TVS=transvaginalsonography; CRL=crown - rump length; increased in nuchal translucency indicates that the baby is at higher risk for Down's syndrome; manning score is used to assess for fetal well-being

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See also Diabetes mellitus in pregnancy: antenatal management

Diabetes mellitus in pregnancy: insulin therapy during antenatal phase

Total daily insulin requirement

The starting insulin dose can be calculated based on the patient's body weight with insulin dose of 0.5 - 0.8 unit/kg/day.

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Insulin regimen

Either one of these 2 regimens are usually used for insulin therapy:

Intensive regimen

2 to 5 pre-meals injections of bolus insulin (rapid/short-acting insulin : regular, aspart, lispro) plus 1 (pre-bed) to 2 (pre-bed + pre-breakfast) injections of basal insulin (intermediate or long-acting insulin : NPH, zinc, extended zinc, lispro-protamine, glargine) are given . Example of the regimen is, 3 pre-meals injections (pre-breakfast, pre-lunch, pre-dinner) of actrapid, plus 1 pre-bed injection of NPH. Generally, requirement for basal insulin is 50% to 70% of total daily insulin requirement, and requirement for pre-meals bolus insulin is 30% to 50% of total daily insulin requirement.

Example of calculation:

Body weight : 50 kg

Total daily insulin requirement : 0.5 x 50 = 25 units

Regimen : 3 pre-meals actrapid injections + 1 pre-bed NPH injections

=Intensive regimen of 3 pre-meals injections (pre-breakfast, pre-lunch, pre-dinner) of actrapid, plus 1 pre-bed injection of NPH

Dose of 3 pre-meals actrapid : 

50% of total daily insulin requirement (50 to 70%)

=50% x 25 unit

=12.5 unit

Therefore,

Dose for each pre-meal actrapid

= 12.5 unit / number of meals

= 12.5 unit / 3

=4.16unit ~ 4 unit

Dose of 1 pre-bed NPH :

50% of total daily insulin requirement (30 to 50%)

=50% x 25 unit

=12.5 unit ~ 13 unit

or,

Dose of 3 pre-meals actrapid : 

70% of total daily insulin requirement (50 to 70%)

=70% x 25 unit

=17.5 unit

Therefore,

Dose for each pre-meal actrapid

= 17.5 unit / number of meals

= 17.5 unit / 3

=5.83unit ~ 6 unit

Dose of 1 pre-bed NPH :

30% of total daily insulin requirement (30 to 50%)

=30% x 25 unit

=7.5 unit ~ 8 unit

Conventional regimen

1-2 injections of a mixture of rapid/short-acting and intermediate-acting insulins is given. Twice daily injections are preferred for better glycemic control. With the 2-injection regimen, generally two-thirds of the total daily insulin requirement is given before breakfast and one-third is given before the evening meal.

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If after around 3 days started insulin with the calculated dose the patient does not achieve the desired level of glycemic control, the insulin dose is titrated accordingly.

-Example of insulin titration algorithm-
Generally, glucose level of 4 - 6 or 7 mmol/l is acceptable, therefore, usually the algorithm is not followed too strictly
Refer conversion table below for unit conversion

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(See also Diabetes mellitus: antenatal management)

Diabetes mellitus in pregnancy: antenatal management

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Management of diabetes mellitus in pregnancy can be divided into phases:

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These are the crucial components in the management of diabetes mellitus in pregnancy during antenatal period:

1. Dating
2. Glucose level assessment
3. Glucose control
4. Management of complications
5. Determination of mode and timing of delivery

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Dating

Accuracy of gestational age is really important for the management of diabetes mellitus in pregnancy, especially for determination of timing of delivery. The earlier dating is done, which is done by using ultrasound, the more accurate the estimated gestational age of the fetus.

There is some special cases in which early dating is not done, and the dates are not certain. In such cases, amniocentesis might need to be done, to check for lecithine syringomyeline (L:S) ratio, to assess for fetal lung maturity.

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Glucose level assessment

Blood sugar profile (venous blood sugar) is usually done monthly or every 2 weeks, aim to achieve blood sugar level of 4 - 6 mmol/L. It reflects the recent blood sugar control.

Meanwhile, HbA1c is done once in each trimester, with target of HbA1c <6 - 7%. It reflects the glucose control for the previous 2 - 3 months, hence, also reflects the adequacy of BSP testing schedule.

Blood sugar home monitoring (capillary blood sugar) is recommended for all patients.

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Glucose control

Blood sugar level is controlled either by diet control or by using subcutaneous insulin. Oral anti-diabetic agents are not recommended because of the teratogenic risk.

If sugar control is not achieve by diet control only, then the use of subcutaneous insulin is initiated.

Different consultant might prefer different regimen of insulin. Common regimen used is a regimen of three premeal injections of short acting insulin. There are also other regimen that can be used such as a twice daily regimen of short and intermediate acting insulin. See also Diabetes mellitus in pregnancy: insulin therapy during antenatal phase

The aim of premeal blood sugar level range from 4 to 6 mmol/L.

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Management of complications

Early detection of complications is important, either maternal complications or fetal complications.

See also Diabetes mellitus in pregnancy: ultrasound work up during antenatal phase

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Determination of mode and timing of delivery

Optimally controlled of the diabetes, the pregnancy should be allowed to at least 38 - 39 weeks, but not to go beyond the expected date of delivery.

Poorly controlled diabetes might need earlier delivery, usually because of the complication, such as macrosomic baby.

Vaginal delivery is the mode of delivery if there is no other obstetric complications such as dysfunctional labour, which may call for emergency caesarean section.

Elective caesarean section should be considered in women with:

• Bad obstetric history
• History of subfertility
• Poor diabetic control
• Vascular complications
• Macrosomia

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*Antenatal visit frequency

Antenatal visits should be done every 2 weeks until 32 - 34weeks and then weekly thereafter.

Chronic liver disease: Child - Pugh Score

Child - Pugh score has been used as a prognostic tool for patient with chronic liver disease / cirrhosis. It is seldom useful in the management of the disease except in case of hepatocellular carcinoma, which Child - Pugh score is included in the assessment to determine wether the liver is resectable or not.

Child - Pugh score divides patients into 3 categories: A, B, and C. These categories are determined by the total sum of points from each of those 5 criteria.