The document outlines the screening and diagnosis of gestational diabetes mellitus (GDM), detailing its definition, prevalence, risk factors, and the importance of diagnosis and treatment for both mother and baby. It emphasizes the need for appropriate screening measures, highlighting guidelines for when and whom to screen, as well as diagnostic criteria. Long-term follow-up is crucial as many women with GDM develop type 2 diabetes post-pregnancy.

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, 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

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
Buchanan, Wiang, Kjos, Watanabe 2007

6. Prevalence
• The prevalence of GDM is estimated to be 10-
16.9% 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
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?

8. Risk factors for GDM
High risk
• 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
Low risk
• 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
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
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
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

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, 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 24-28 weeks gestation.
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%
or
• Random >200mg/dl (11.1 mmol/L)
or
• 2hr value in OGTT >200mg/dl (11.1 mmol/L)
• If overt diabetes is detected, it must be treated appropriately.
ADA, 2015

16. When to screen
Screening for GDM
• Screening should be done at 24-28 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 92 - 125 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
World Health Organization, 2013

17. Diagnostic criteria
WHO (2013)
1 or more
IADPSG
1 or more
ADA
“one step”
ADA
“two step”
Fasting
plasma
glucose
5.1-6.9
mmol/L
(92-125
mg/dl)
>5.1 mmol/L
(92 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)
>10.0mmol/L
(180mg/dl)
>10.0mmol/L
(180mg/dl)
2 hour PG
after 75gm
load
8.5-11.0
mmol/L (153-
199 mg/dl)
>8.5 mmol/L
(153 mg/dl)
>8.5 mmol/L
(153 mg/dl)
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, 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.

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)

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 2015. 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):S105-111.
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):S168-183.
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):2362-2367.
IDF Diabetes Atlas 6th Ed, 2013
Kim C. Newton KM, Knopp RH. Gestational diabetes and the incidence of type 2 diabetes. Diabetes Care
2002;25:1862-1868
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):S251-260.
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