1. Gestational diabetes GP Obstetric Shared Care Program Accreditation Seminars
Shantha Joseph
Endocrinologist
Obstetric physician
Sothern Adelaide Local Health Network

2. Objectives Overview of gestational diabetes Diagnostic criteria
Recommendations for management
Case discussions

3. GDM glucose intolerance of variable severity with onset or first recognition during pregnancy.
The diagnosis of GDM includes those women with previously undiagnosed abnormalities of glucose tolerance, as well as women with glucose abnormalities related to the pregnancy alone.
A definitive diagnosis of non‐gestational diabetes cannot be made until the post partum period

4. Gestational Diabetes Mellitus (GDM)
Most frequent metabolic complication of pregnancy
Gestational diabetes is generally defined as diabetes with initial onset or recognition during pregnancy
Accounts for 90% of diabetes in pregnancy
Affects ~7% of all pregnancies (range 1-14%) Highest in ethnic groups with high frequencies of type 2 diabetes (Aboriginal, Asian, and Pacific Island ancestry)
independent of changes in definition,the prevalence of gestational diabetes is increasing

5. Changes in maternal glucose and insulin sensitivity in pregnancy
Pregnancy results in profound changes in maternal metabolism
During normal pregnancy there is a major change in insulin sensitivity
marked fall in insulin sensitivity late in pregnancy, seen by all investigators
50–70% reduction in insulin sensitivity in women with gestational diabetes compared with controls
In response to the insulin resistance,insulin secretion is increased and the net change in glucose for the majority of women increase is relatively small,
Plasma glucose declines with pregnancy
may reflect both dilutional effects and increased use by the foeto- placental unit

6. Main driver- TNF alpha
discuss- adiposity- survival edge for human baby

7. the main biological difference between women with gestational diabetes and others is a failure of insulin secretion to rise in response to the physiological insulin resistance of pregnancy
? Underlying genetic factors
Environmental co-factors
failure of beta cell to produce increased insulin in response to the increased resistance- various causes
several groups have examined genes associated
with type 2 diabetes (almost all of which affect insulin
secretion rather than insulin sensitivity12) and found that polymorphisms
associated with type 2 diabetes may also be present
in women with gestational diabetes.13 While of mechanistic
interest it should be noted that currently known genetic variation
accounts for a very small part of the variance of type 2 diabetes risk12 and so, at current levels of knowledge, may contribute
only modestly to prediction of gestational diabetes risk

8. Consequences of GDM Fetal Morbidity Maternal Morbidity Hypertension
Preeclampsia
Increased likelihood of C-section
Development of diabetes after pregnancy
Fetal Morbidity
Macrosomia (excessive birth weight)
Neonatal hypoglycemia
Polycythemia
Increased perinatal mortality
Congenital malformation
Hyperbilirubinemia
Respiratory distress syndrome
Hypocalcemia

9. Diagnostic criteria and recommendations for management
Review of literature

10. Objective: to clarify the risks of adverse outcomes associated with various degrees of maternal glucose intolerance less severe than that in overt diabetes mellitus
23,316 pregnant women without overt diabetes
15 centers in 9 countries over 6 years (July 2000 – April 2006)

14. Protocol Limitations No universal protocol
Impossible to compare different studies of GDM
? true prevalence of GDM
? risks associated with maternal hyperglycemia

15. Consensus Needed for New Criteria
International Association of Diabetes in Pregnancy Study Groups (IADPSG)
2008 conference to review HAPO and related studies data
Establish new diagnostic criteria for GDM

17. SAPPG
OGTT May be performed at any time during pregnancy if symptoms and signs of abnormal glucose tolerance e.g. excess thirst; polyuria, polyhydramnios, macrosomia
Consider an early test (around weeks of gestation) for women with a past history of gestational diabetes if a recent OGTT has not been performed
Women with known glucose intolerance outside pregnancy may be considered to have gestational diabetes from the time of conception and therefore a repeat OGTT is not required

18. Universal screening at 26-28 weeks GA – OGCT
If positive proceed to OGTT

19. ADIPS 2002 High risk factors: Glycosuria; Age over 30 years; Obesity;
Family history of diabetes;
Past history of GDM or glucose intolerance;
Previous adverse pregnancy outcome; and
Belonging to an ethnic group with a high risk for GDM

20. ADIPS 2013
Recommendations for early testing for GDM for women with high risk
• Previous GDM
• Previously elevated blood glucose level
• Ethnicity: Asian, Indian, Aboriginal, Torres Strait Islander, Pacific Islander, Maori, Middle Eastern, non‐white African
• Maternal age ≥40 years
• Family history DM (1st degree relative with diabetes or a sister with GDM)
• Obesity, especially if BMI > 35 kg/m2
• Previous macrosomia (baby with birth weight > 4500 g or > 90th centile)
• Polycystic ovarian syndrome
• Medications: corticosteroids, antipsychotics
The diagnosis of GDM will therefore include those women with previously undiagnosed abnormalities of glucose tolerance, as well as women with glucose abnormalities related to the pregnancy alone. A definitive diagnosis of non‐gestational diabetes cannot be made until the post partum period. ADIPS does not currently recommend the use of the term “Overt Diabetes” (as proposed by IADPSG) to describe marked hyperglycaemia (consistent with diabetes if detected outside pregnancy) first detected in pregnancy. However, clinical judgement should be used to detect marked hyperglycaemia especially in early pregnancy (first visit). These women are at higher risk of major pregnancy complications and require urgent attention, including evaluation for other complications of the undiagnosed diabetes.
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21. ADIPS 2013
All women not known to have GDM, should have a 75g OGTT at 24–28 weeks gestation
A diagnosis of GDM is made if one or more of the following glucose levels are elevated;
Fasting glucose ≥ 5.1mmol/L
1‐hr glucose ≥ 10.0mmol/L
2‐hr glucose ≥ 8.5mmol/L

22. How does this compare with the existing protocol
Current protocol based on ADIPS 2002
New ADIPS recommendations- not accepted yet
Universal screening at weeks with GCT- 50 gm glucose- ≥ 7.8 mmol/L
If positive – 75gm OGTT
High risk – 75 gm OGTT at time of contact with health system
All others OGTT at weeks
OGTT Diagnostic criteria
Fasting glucose ≥ 5.5mmol/L
2‐hr glucose ≥ 7.8 mmol/L (SAPPG- 8.0 mmol/l)
Fasting glucose ≥ 5.1mmol/L
2‐hr glucose ≥ 8.5mmol/L
Therapeutic criteria
fasting glucose level <5.5 mmol/L
• 2 hour glucose level <7.0 mmol/L
Fasting glucose ≤ 5.0mmol/L
2 hour glucose ≤ 6.7mmol/L

23. Current practice in SA

24. Diagnostic criteria for Gestational Diabetes
SAPPG-Based on ADIPS criteria- 2002
Universal screening plus high risk patients screened earlier
The recommended screening test for GDM- OGCT
performed at weeks' gestation and positive results are:
1 hour venous plasma glucose level 7.8 mmol/L after a 50 g glucose load (morning, non-fasting);
Confirmation of diagnosis after a positive screening test:OGTT
a 75 g oral glucose tolerance test (fasting) with a venous plasma glucose level at
0 hours of 5.5 mmol/L and/or at
2 hours of 8.0 mmol/L.

25. Post diagnosis Review by Diabetes nurse educator –
group session with DNE and dietician
BGL monitoring, provision of glucometer and forms for NDSS-for supplies
BGL monitoring- 4 times a day
Fasting, 2 hours after BF, lunch and dinner
Targets- fasting <5.5 mmol/L and post meal<7 mmol/L
Review in Obs med clinic- usually 1-2 visits unless issues present
Phone contact with DNE

26. Imaging studies
Ultrasound for fetal size at least once at 36 to 37 wk; more frequently if macrosomia suspected
Fetal echo if required
Antenatal testing
Routine blood pressure and urine protein monitoring

27. Non-pharm Rx Regular moderate exercise
Dietary modifications aimed at glycemic control:
low-fat, high-fiber diet; avoid sugar and concentrated sweets; and eat small, frequent meals.
Nutrition counseling for diet that adequately meets the needs of pregnancy but restricts carbohydrates to 35% to 40% of daily calories.
For women with a body mass index >30, restrict calories to 25 kcal/kg actual weight per day.

28. Pharmacologic Rx
Start if BSLs > cutoff on at least 2 occasions during same time period of the day
Clinical judgement
re-educate – DNE review
If fasting values are elevated, use NPH at bedtime
If postprandial values are elevated, use ultra rapid-acting insulin before meals
Metformin in select patients
with initial dose of 0.2 U/kg protaphane
NR- with initial dose 1.5 U/10 g carbohydrate at breakfast and 1 U/10 g carbohydrate at lunch and dinner

29. Post-partum Glucose profile on day 3-4 post partum
All women with gestational diabetes should have a glucose tolerance test at 6-12 weeks post partum
The Gestational Diabetes Recall Register should be offered (if the woman has not already been recruited to this) to facilitate long-term follow-up

30. cases

31. Ms BY
28 year old recently migrated from Canada
BMI-24
Non smoker, nil medical issues
Maternal grandmother had late onset T2DM

32. When to test? Issues of concern Best place of care Pros and cons
Ongoing nausea- unable to tolerate GCT
Alternative diagnostic tests include capillary blood glucose monitoring (fasting and postprandial over a week and review
Alternative diagnostic tests
Alternative diagnostic tests include capillary blood glucose monitoring (fasting and postprandial – see below) over a number of days, particularly if there has been previous intolerance of glucose loading

33. Alternative Approaches
Jelly beans for GDM screening (AJOG 1999;181:1154–1157) 50 g glucose beverage is intensely sweet 15-20% of patients experience nausea and vomiting (voids test)
28 Brach’s No. 110 jelly beans = 50 g glucose
Poor sensitivity compared to beverage (40 vs. 80%, respectively)

34. HAPO
Hb A1c-not a useful alternative to OGTT
ADIPS 2013-
measurement of HbA1c - level of ≥ 48mmol/mol (6.5%) is diagnostic of GDM and very likely represents previous undiagnosed type 2 diabetes
Can be considered-
In areas where the rate of undiagnosed type 2 diabetes is thought to be high,
In remote areas where the performance of a GTT may be logistically difficult,

35. Ms AZ 42 year old primi,
Caucasian
History of PCOS
Obese, non-smoker
Family history of DM- brother and father- T2DM

36. When to test? Issues of concern Best place of care Pros and cons
GCT- 8.5 mmol/L
OGTT-
F-5.9 mmol/L
2h PP- 9.1 mmol/L
BSL monitoring
Raised BSL in fasting column >2 x in a fortnight
Ongoing hyperglycemia- Rx options
Needle phobic- teary 16 weeks GA- options

37. Metformin
Metformin versus Insulin for the Treatment of Gestational Diabetes MiG Trial NEJM 2008
showed that use of metformin gives comparable outcomes to insulin in the management of women with gestational diabetes.
Women treated with metformin had offspring with less severe neonatal hypoglycaemia.
They gained less weight during pregnancy and lost more weight after delivery.
Women preferred treatment with metformin.
Follow up of the offspring to date has shown no difference between those whose mothers were treated with insulin and those whose mothers were treated with metformin

38. Summary
GDM glucose intolerance of variable severity with onset or first recognition during pregnancy.
Important to recognise as maternal and fetal consequences can be dangerous
SAPPG in line with ADIPS no change to criteria for diagnosis or management till further research- which is being planned
Alternative approaches for diagnosis-
BSL monitoring x 1 week
HbA1C
Alternative approaches for Rx
Metformin vs insulin
Post partum- critical to do OGTT

39. Thank you