1. Screening and Diagnosis

2. Objectives At the end of this session you will be able to: Define GDM
Identify the risks for development of GDM.
State the prevalence of GDM locally
Explain the reason for identifying and treating GDM
Identify appropriate screening measures
Identify who should be screened
Identify diagnostic criteria

3. Definition
Glucose intolerance with onset or first recognition during pregnancy
Characterized by β-cell function that is unable to meet the body’s insulin needs
Buchanan T, Xiang A, Kjos S, Watanabe R. What is gestational Diabetes? Diabetes Care 2007;30(2):S
Buchanan, Wiang, Kjos, Watanabe 2007

4. Glucose regulation during pregnancy
Insulin resistance begins in mid pregnancy and progresses through the third trimester
A result of maternal adiposity and effects of placental hormones
β -cells usually make more insulin to compensate for resistance – when they cannot meet the needs hyperglycemia occurs
All women who are pregnant have increasing insulin resistance. Most women are able to increase the secretion of insulin to overcome the resistance and therefore they do not experience higher than normal blood glucose levels.
Those women who cannot secrete more insulin develop gestational diabetes.

5. GDM represents a state of chronic β-cell dysfunction in the face of insulin resistance
Insulin resistance and insulin levels are different prior to pregnancy in women who develop GDM and those who do not
Changes in insulin sensitivity are similar in both groups during pregnancy
However in GDM women, insulin secretion does not increase adequately
While all women become insulin resistant and all increase their insulin secretion, studies have shown a difference in the women who develop GDM. This suggests that GDM is really a forerunner to type 2 diabetes, and may explain why so many women with GDM go on to develop type 2.
Buchanan T, Xiang A, Kjos S, Watanabe R. What is gestational Diabetes? Diabetes Care 2007;30(2):S
Buchanan, Wiang, Kjos, Watanabe 2007

6. Prevalence
The prevalence of GDM is estimated to be % in pregnant women depending on the diagnostic criteria used.
Prevalence also varies by region and ethnicity.
Highest prevalence is in South East Asia
Lowest in North America and the Caribbean
Prevalence higher
in less physically active women.
In older women
In women with higher BMI
In those with a strong family history of diabetes
Prevalence is the number of people said to have the condition at one point in time.
Using the 1999 WHO criteria prevalence is approximately10%
Using the 2008 IADPSG criteria the prevalence is approximately 15%
IDF Atlas 6th Edition reports the global prevalence of hyperglycemia in pregnancy (women years) to be 16.9%
WHO. Diagnostic Criteria and Classification of Hyperglycaemia First Detected in Pregnancy , 2013
IDF Diabetes Atlas 6th Ed, 2013
WHO, 2013
IDF, 2013

7. Discussion What are the risk factors for gestational diabetes?
What risk factors do you see most often in your setting?
Facilitator: Stop you presentation here and ask the questions…
You could write the answers on butcher paper or on a black/white board.
If one risk factor is most commonly seen – such as obesity – you could ask why that is occurring.

8. Risk factors for GDM Low risk High risk Age less than 25 years
Obesity
Diabetes in 1st degree relative
Previous
history of GDM or glucose intolerance
complicated pregnancy
infant with macrosomia > 3.5 kg
Older age
High risk ethnic group; South Asian, East Asian, Indigenous American or Australian, Hispanic
PCOS
Age less than 25 years
No previous poor pregnancy outcomes
No diabetes in 1st degree relatives
Normal prepregnancy weight and weight gain during pregnancy
No history of abnormal glucose tolerance
Now compare the list that you just developed from the participants with this list.
Perkins JM, Dunn JP, Jagastia SM. Perspectives in gestational diabetes mellitus: A review of screening, diagnosis and treatment. Clinical Diabetes. 2007;25(2):57-62
Perkins, Dunn, Jagastia, 2007

9. Is Hypertension a risk factor?
Hypertension prior to pregnancy or during 1st trimester – doubled the risk of GDM – independent of maternal weight
Hence all women with hypertension should be screened for GDM
This question might result in some discussion… BP is not currently recommended as a screening tool, but is it something that should be considered. How many take the BP on the 1st pregnancy visit?
Hedderson MM, Ferrara A. High blood pressure before and during early pregnancy is associated with an increased risk of gestational diabetes mellitus. Diabetes Care. 2008;31(12):
Hedderson, Ferrara, 2008

10. Why diagnose and treat GDM?
Short term risks for the mother
Development of gestational hypertension, worsening essential hypertension or development of preeclampsia
Operative delivery - related to macrosomia
Polyhydramnios
Premature labour
Long term risks for the mother
Development of type 2 diabetes in next ~10 years (30-60% depending on population)
Development of cardiovascular disease
Canadian Diabetes Association Clinical Practice Guidelines Expert Committee. Canadian Diabetes Association 2008 Clinical practice guidelines for the prevention and management of diabetes in Canada; Diabetes and pregnancy. Can J of Diabetes. 2013;37(suppl 1):S
Metzger BE, Buchanan TA, Coustan DR, De Leiva A, Hadden DR, Hod M. Summary and recommendations of the fifth international workshop-conference on gestational diabetes mellitus, Diabetes Care. 2007; 30(suppl 2):S
CDA, 2013
Metzger, Buchanan, et al. 2007

11. Why diagnose and treat GDM?
Short term risks for the baby
Macrosomia
Neonatal hypoglycemia
Jaundice
Preterm birth
Birth injury
Hypocalcemia/ hypomagnesimia
Respiratory distress syndrome
Long term risks for the baby
Obesity
Type 2 diabetes
Neonatal hypoglycemia is directly proportional to the state of glycemia of the mother at the time of labour and delivery.

12. Importance of follow up
Long term follow up studies have shown that most women with GDM will develop diabetes within the first decade after the pregnancy
Testing after pregnancy is important - more about this later
Kim C. Newton KM, Knopp RH. Gestational diabetes and the incidence of type 2 diabetes. Diabetes Care 2002;25:
Kim, Newton, Knopp 2002

13. Screening
Whom to screen
When to screen
How to screen

14. Who to screen
Some guidelines recommend screening all women at the first visit to rule out pre- existing type 2 diabetes Most guidelines recommend screening all women for GDM at weeks gestation.
Screening at the first visit has become important as the prevalence of type 2 diabetes has increased in the younger population. Many women may not be aware they have type 2 diabetes when they become pregnant.
ADA, 2015
CDA , 2013

15. When to screen? First trimester
Screening in 1st trimester
- to rule out unidentified pre-existing diabetes
Fasting plasma glucose >126 mg/dl (7 mmol/L) or
HbA1c >6.5%
Random >200mg/dl (11.1 mmol/L)
2hr value in OGTT >200mg/dl (11.1 mmol/L)
If overt diabetes is detected, it must be treated appropriately.
Ask the participants – when do you usually see women for the 1st pregnancy visit?
Do you think you should screen them before the week period?
Recommended that all women be screened at first visit.
ADA. Standards of Medical Care in Diabetes Diabetes Care. 2015;38(Suppl 1):S13
ADA, 2015

16. When to screen Screening for GDM
Screening should be done at weeks
Diagnosis based on a 75 gm glucose load given in fasting state
GDM diagnosed when one or more of the following is present
Fasting mg/dl (5.0 – 6.9 mmol/L)
1 hour post 75 gm load >180 mg/dl (10 mmol/L)
2 hour post 75 gm load >153mg/dl (8.5 mmol/L)
If woman tests negative, screening at 32 weeks also may be necessary in presence of high risks
The recommended screen for gestational diabetes is to have the woman come to the lab or clinic fasting.
A blood sample is drawn, then a 75 gm glucose load is given, this should be sipped and completed in 5-10 minutes.
A blood samples are then drawn at 1 and 2 hours after the drink is taken.
Gestational diabetes is diagnosed when one or more of the criteria is met.
The reason there is a range of mg/dl ( mmol/L) is that if the fasting level is over 126mg/dl or 7 mmol/L the woman would be diagnosed with diabetes – after a second confirming test.
World Health Organization. About diabetes. Cited May 10, 2013 from
World Health Organization, 2013

17. Diagnostic criteria Fasting plasma glucose 5.1-6.9 mmol/L
WHO (2013)
1 or more
IADPSG
ADA
“one step”
“two step”
Fasting plasma glucose
mmol/L
( mg/dl)
>5.1 mmol/L
(92 mg/dl)
50-g glucose load (nonfasting) If 1 hour > 7.8mmol/L (140mg/dl) –
Do 100 g OGTT
GDM If 2 of 4 results high
1 hour PG after 75gm load
>10.0mmol/L (180mg/dl)
2 hour PG after 75gm load
mmol/L ( mg/dl)
>8.5 mmol/L
(153 mg/dl)
This slide simply shows a comparison of different screening methods.
Note: the 2015 NICE guidelines opted for a 5.6-mmol/L (101-mg/dL) cutoff using a one-step single fasted 75-g 2-hour oral glucose tolerance test [OGTT] (and/or 2-hour glucose of > 7.8 mmol/L).
ADA 2 step method
After the 100 g OGTT
Fasting 95mg/dl(5.3(mmol/L) or Fasting 105 mg/dl(5.8 mmol/L)
1 hr 180 mg/dl (10 mmol/L) 1 hr 190 mg/dl (10.6 mmol/L)
2 hr 155 mg/dl (8.6 mmol/L) 2 hr 165 mg/dl (9.2 mmol/L)
3 hr 140 mg/dl (7.8 mmol/L) 3 hr 145 mg/dl (8 mmol/L)
Mohan V, Mahalakshmi MM, Bhavadharini B, Maheswari K, Kalaiyarasi G, Anjana RM, Uma R, Usha S, Deepa M, Unnikrishnan R, Pastakia SD, Malanda B, Belton A, Kayal A. Comparison of screening for gestational diabetes mellitus by oral glucose tolerance tests done in the non-fasting (random) and fasting states. Acta Diabetologica. 2014;51:
Diabetes Care 2015, WHO 2013

18. How to screen
Key considerations for screening in low resource countries
Low cost
No requirement for elaborate preparation
High sensitivity and specificity
Short turn-around time
Be administered by health workers with minimal training
Need little maintenance, calibration, or refrigeration
Agarwal et al - Fasting plasma glucose as a screening test for gestational diabetes mellitus, Archives of Gynecology and Obstetrics 2007
Agarwal et al, 2007

19. Venous or capillary The venous plasma is the gold standard
Where laboratory facilities or technicians are not available, capillary glucose estimations may be done using a hand held glucose meter.
The glucose meter must be standardized with a lab and calibrated against the lab on a regular basis.
If facilities are not available, a capillary sample should be taken but the result should be confirmed as soon as possible with a venous sample taken at an appropriate facility.
There is no need to adjust the capillary result as meters have been adjusted to report venous levels in the factory.
Das, V, Jain V, Afarwal A, Pandey A et al Glucometer screening of gestational diabetes. J Obs & Gyn of India. 2006;56(6):
Bhavadharini B, Mahalakshmi MM, Maheswari K, Kalaiyarasi G, Anjana RM, Deepa M, Ranjani H, Priya M, Uma R, Usha S, Pastakia SD, Malanda B, Belton A, Unnikrishnan R, Kayal A, Mohan V. Use of capillary blood glucose for screening for gestational diabetes mellitus in resource-constrained settings. Acta Diabetologica Apr 28. [Epub ahead of print].

20. Which of these women has GDM?
All have had 75g glucose load at about 25 weeks
Rupinder, overweight, 35 years old,
fasting 90 mg/dl (5.0 mmol/L),
1 hr 170mg/d (9.4 mmol/L),
2hr 135mg/dl (7.5 mmol/L)
Joanne, 3rd pregnancy, history of big babies,
fasting 130 mg/dl (7.2 mmol/L),
1 hr 190mg/dl (10.5 mmol/L)
2 hr 220mg/dl (12.2 mmol/L)
Maria, 1st pregnancy, 25 years old, obese,
fasting 90mg/dl (5 mmol/L),
1 hr 168mg/dl (9.3mmol/L)
2 hr 160 mg/dl (8.8mmol/L)
Rupinder does NOT have GDM as her results are all within range… she is however at risk as she is overweight, 35 years old – should she be retested? When? Answer : at about 32 weeks
Manju – does NOT have GDM, she has diabetes – both her fasting level and 2 hr PG are above diagnostic levels for diabetes. Technically she would be said to have GDM because it was discovered during pregnancy, but what should be done once she has delivered?
Ashima – DOES have GDM – her fasting level and 1 hour are normal but her 2 hr PG is above the diagnostic level of 153 mg/dl (8.5 mmol/L).

21. Giving the diagnosis Will my baby be ok? – 1st question often asked
Is this temporary? – 2nd question
Questions provide an opportunity for teaching
Must answer truthfully
Must convey importance of management during pregnancy for healthy outcome but also for future health of baby and mother
Risk of type 2 diabetes
Risk of obesity

22. References
American Diabetes Association. Clinical Practice Recommendations Diabetes Care. 2015;38(1) Agarwal et al - Fasting plasma glucose as a screening test for gestational diabetes mellitus, Archives of Gynecology and Obstetrics 2007 Buchanan T, Xiang A, Kjos S, Watanabe R. What is gestational Diabetes? Diabetes Care 2007;30(2):S Canadian Diabetes Association Clinical Practice Guidelines Expert Committee. Canadian Diabetes Association 2013 Clinical practice guidelines for the prevention and management of diabetes in Canada; Diabetes and pregnancy. Can J of Diabetes. 2013;37(suppl 1):S Hedderson MM, Ferrara A. High blood pressure before and during early pregnancy is associated with an increased risk of gestational diabetes mellitus. Diabetes Care. 2008;31(12): IDF Diabetes Atlas 6th Ed, 2013 Kim C. Newton KM, Knopp RH. Gestational diabetes and the incidence of type 2 diabetes. Diabetes Care 2002;25: Metzger BE, Buchanan TA, Coustan DR, De Leiva A, Hadden DR, Hod M. Summary and recommendations of the fifth international workshop-conference on gestational diabetes mellitus, Diabetes Care. 2007;30(suppl 2):S Perkins JM, Dunn JP, Jagastia SM. Perspectives in gestational diabetes mellitus: A review of screening, diagnosis and treatment. Clinical Diabetes. 2007;25(2):57-62 WHO. Diagnostic Criteria and Classification of Hyperglycaemia First Detected in Pregnancy , 2013