Gestational_Diabetes_Flashcards

Question 1

What percentage of pregnancies are complicated by diabetes mellitus?

Answer 1

Up to 1 in 20 pregnancies.

Question 2

What are the types of diabetes in pregnancy and their prevalence?

Answer 2

87.5% have gestational diabetes, 7.5% have type 1 diabetes, 5% have type 2 diabetes.

Question 3

How common is gestational diabetes in pregnancies?

Answer 3

Affects around 4% of pregnancies.

Question 4

What are the risk factors for gestational diabetes?

Answer 4

BMI of > 30 kg/m², previous macrosomic baby weighing 4.5 kg or above, previous gestational diabetes, first-degree relative with diabetes, family origin with a high prevalence of diabetes (South Asian, black Caribbean, and Middle Eastern).

Question 5

What is the test of choice for screening gestational diabetes?

Answer 5

The oral glucose tolerance test (OGTT).

Question 6

When should OGTT be performed for women who’ve previously had gestational diabetes?

Answer 6

As soon as possible after booking and at 24-28 weeks if the first test is normal.

Question 7

When should OGTT be offered to women with other risk factors?

Answer 7

At 24-28 weeks.

Question 8

What are the diagnostic thresholds for gestational diabetes according to NICE?

Answer 8

Fasting glucose is >= 5.6 mmol/L, 2-hour glucose is >= 7.8 mmol/L.

Question 9

What should be done for newly diagnosed women with gestational diabetes?

Answer 9

Seen in a joint diabetes and antenatal clinic within a week, taught about self-monitoring of blood glucose, given advice about diet and exercise.

Question 10

What is the management if fasting plasma glucose level is < 7 mmol/L?

Answer 10

A trial of diet and exercise should be offered. If glucose targets are not met within 1-2 weeks, metformin should be started. If glucose targets are still not met, insulin should be added.

Question 11

What is the management if fasting glucose level is >= 7 mmol/L?

Answer 11

Insulin should be started.

Question 12

What should be done if plasma glucose level is between 6-6.9 mmol/L with complications?

Answer 12

Insulin should be offered.

Question 13

When should glibenclamide be offered?

Answer 13

For women who cannot tolerate metformin or those who fail to meet the glucose targets with metformin but decline insulin treatment.

Question 14

What is the management of pre-existing diabetes in pregnancy?

Answer 14

Weight loss for women with BMI of > 27 kg/m², stop oral hypoglycaemic agents apart from metformin, commence insulin, folic acid 5 mg/day from pre-conception to 12 weeks gestation, detailed anomaly scan at 20 weeks, tight glycaemic control, treat retinopathy.

Question 15

What are the targets for self-monitoring of pregnant women with diabetes?

Answer 15

Fasting: 5.3 mmol/L, 1 hour after meals: 7.8 mmol/L, 2 hours after meals: 6.4 mmol/L.

Question 16

summarise GDM

Answer 16

Gestational diabetes

Diabetes mellitus may be a pre-existing problem or develop during pregnancy, gestational diabetes. It complicates up to 1 in 20 pregnancies. NICE estimates the following breakdown:
87.5% have gestational diabetes
7.5% have type 1 diabetes
5% have type 2 diabetes

Gestational diabetes

Gestational diabetes is the second most common medical disorder complicating pregnancy (after hypertension), affecting around 4% of pregnancies.

Risk factors for gestational diabetes
BMI of > 30 kg/m²
previous macrosomic baby weighing 4.5 kg or above
previous gestational diabetes
first-degree relative with diabetes
family origin with a high prevalence of diabetes (South Asian, black Caribbean and Middle Eastern)

Screening for gestational diabetes
the oral glucose tolerance test (OGTT) is the test of choice
women who’ve previously had gestational diabetes: OGTT should be performed as soon as possible after booking and at 24-28 weeks if the first test is normal. NICE also recommend that early self-monitoring of blood glucose is an alternative to the OGTTs
women with any of the other risk factors should be offered an OGTT at 24-28 weeks

Diagnostic thresholds for gestational diabetes
these have recently been updated by NICE, gestational diabetes is diagnosed if either:
fasting glucose is >= 5.6 mmol/L
2-hour glucose is >= 7.8 mmol/L

Management of gestational diabetes
newly diagnosed women should be seen in a joint diabetes and antenatal clinic within a week
women should be taught about self-monitoring of blood glucose
advice about diet (including eating foods with a low glycaemic index) and exercise should be given
if the fasting plasma glucose level is < 7 mmol/l a trial of diet and exercise should be offered
if glucose targets are not met within 1-2 weeks of altering diet/exercise metformin should be started
if glucose targets are still not met insulin should be added to diet/exercise/metformin
gestational diabetes is treated with short-acting, not long-acting, insulin
if at the time of diagnosis the fasting glucose level is >= 7 mmol/l insulin should be started
if the plasma glucose level is between 6-6.9 mmol/l, and there is evidence of complications such as macrosomia or hydramnios, insulin should be offered
glibenclamide should only be offered for women who cannot tolerate metformin or those who fail to meet the glucose targets with metformin but decline insulin treatment

Management of pre-existing diabetes
weight loss for women with BMI of > 27 kg/m^2
stop oral hypoglycaemic agents, apart from metformin, and commence insulin
folic acid 5 mg/day from pre-conception to 12 weeks gestation
detailed anomaly scan at 20 weeks including four-chamber view of the heart and outflow tracts
tight glycaemic control reduces complication rates
treat retinopathy as can worsen during pregnancy

Targets for self monitoring of pregnant women (pre-existing and gestational diabetes)

Time Target
Fasting 5.3 mmol/l
1 hour after meals 7.8 mmol/l, or:
2 hour after meals 6.4 mmol/l

Question 17

A 36-year-old woman with a strong family history of diabetes is currently 28 weeks pregnant in her first pregnancy.

After completing the oral glucose tolerance test, she has unfortunately been diagnosed with gestational diabetes. Her fasting glucose was 7.1mmol/L with 2-hour glucose of 8.9mmol/L.

What is the most appropriate management option in this scenario?

Glibenclamide
Insulin
Lifestyle measures only
Metformin
Metformin and lifestyle interventions

Answer 17

Insulin

If at the time of diagnosis of gestational diabetes, the fasting glucose level is >= 7 mmol/l immediate insulin (plus or minus metformin) should be started
Important for meLess important
If at the time of diagnosis, the fasting glucose level is greater than, or equal to, 7mmol/L, insulin (plus/minus metformin) should be started.

Glibenclamide should only be offered for women who cannot tolerate metformin or those who fail to meet the glucose targets with metformin but decline insulin treatment.

Lifestyle measures (low glycaemic index diet/ exercise) should be tried first if the fasting plasma glucose level is < 7 mmol/L.

Metformin is started when the fasting glucose level is <7mmol/L and glucose targets are not met within 1-2 weeks of lifestyle measures.

Question 18

A 32-year-old woman is referred to the joint antenatal and diabetic clinic after being diagnosed with gestational diabetes mellitus. She is currently 25 weeks pregnant and this is her first pregnancy. There is no history of any pregnancy-related problems in her family but her father has type 1 diabetes mellitus. The examination is normal, other than a raised BMI of 32 kg/m².

Which of the following would be diagnostic for this woman’s condition?

2-hour glucose level >= 5.6 mmol/L
Fasting plasma glucose >= 5.6 mmol/L
Glucose >= 6.4 mmol/L 2-hours after mealtime
Glucose >=7.8 mmol/L 1-hour after mealtime
Random plasma glucose >= 7.8 mmol/L

Answer 18

Fasting plasma glucose >= 5.6 mmol/L

Gestational diabetes can be diagnosed by either a:
fasting glucose is >= 5.6 mmol/L, or
2-hour glucose level of >= 7.8 mmol/L
‘5678’

This patient has been diagnosed with gestational diabetes mellitus in her first pregnancy - she was at an increased risk of this due to her raised BMI and the presence of a first-degree relative with diabetes mellitus. Women with risk factors and no previous history of gestational diabetes mellitus undergo an oral glucose tolerance test at around 24 weeks. Gestational diabetes mellitus is diagnosed if the patient has fasting glucose above 5.6 mmol/L or 2-hour glucose above 7.8 mmol/L on either of these occasions. The correct answer is therefore fasting plasma glucose of above 5.6 mmol/L.

A 2-hour glucose level above 5.6 mmol/L would not be diagnostic of gestational diabetes mellitus. The 2-hour glucose level needs to be above 7.8 mmol/L for diagnosis.

Glucose of 6.4 mmol/L 2-hours after mealtime is one of the glucose targets for women with gestational diabetes mellitus so this answer is not correct.

Glucose of 7.8 mmol/L 1-hour after mealtime is another glucose target for women with gestational diabetes mellitus so this is not the correct answer.

Random plasma glucose tests are not part of the diagnostic process for gestational diabetes mellitus.

Question 19

A 30 year old type 2 diabetic presents to the diabetics clinic advising that she wishes to become pregnant. The patient normally has good glycaemic control and is currently being treated with metformin and gliclazide. What advice should you give her about potential changes to her medication during pregnancy?

Patient may continue on metformin but gliclazide must be stopped
Patient can continue on both medications
Patient may continue on gliclazide but metformin must be stopped
Both drugs must be stopped and the patient must be switched to insulin
Both drugs must be stopped and the patient must be switched to liraglutide

Answer 19

Patient may continue on metformin but gliclazide must be stopped

The correct answer is that the patient may be continued on metformin but that the gliclazide must be stopped. In the management of type 2 diabetes in pregnancy ‘women with pre-existing diabetes can be treated with metformin, either alone or in combination with insulin’. While it is likely that the patient will be required to switch to insulin it is not an absolute requirement. Both gliclazide and liraglutide are contraindicated in pregnancy.

Source: BNF (https://www.evidence.nhs.uk/formulary/bnf/current/6-endocrine-system/61-drugs-used-in-diabetes/612-antidiabetic-drugs

Question 20

A 32-year-old woman presents to the obstetric clinic at 30 weeks gestation. She has been diagnosed with gestational diabetes and was started on metformin two weeks previously. Despite a well controlled diet and maximum dose metformin, her blood glucose levels remain too high.

What is the next most appropriate step to control blood glucose in this woman?

Add on a sulfonylurea and review in two weeks
Stop metformin as start insulin therapy
Add on an sodium-glucose co-transporter-2 (SGLT-2) antagonist and review in one week
Add on insulin therapy
Continue metformin and review in two weeks

Answer 20

Add on insulin therapy

In gestational diabetes, if blood glucose targets are not met with diet/metformin then insulin should be added

This woman has gestational diabetes and hyperglycaemia associated with this can result in macrosomia, premature birth and stillbirth. It is therefore vital that glucose levels are brought under control as quickly as possible. NICE state that ‘if blood glucose targets are not met with diet and exercise changes plus metformin, offer insulin as well’.1 Adding on insulin therapy is therefore the most appropriate thing to do.

Sulfonylureas are not as effective as the metformin and insulin combination in pregnancy.² In addition, they have been shown to be teratogenic in animals. They are therefore not indicated in gestational diabetes.

Stopping metformin would not be ideal as it increases sensitivity to insulin, something which is lacking during pregnancy. Instead, it is safe to continue metformin while adding insulin therapy.

Sodium-glucose co-transporter-2 (SGLT-2) antagonists are also associated with teratogenic effects in animals. They are a very useful option for diabetes management in patients with congestive heart failure due to their diuretic effects.

Continuing metformin alone for a further two weeks in spite of persistently high blood glucose will increase the risk of complications. Insulin should be added at this stage.

1 NICE (2015). Diabetes in pregnancy: management from preconception to the postnatal period
² BMJ (2015). Glibenclamide, metformin, and insulin for the treatment of gestational diabetes: a systematic review and meta-analysis.