Gestational diabetes is diabetes that develops during pregnancy. It is diagnosed either pre-existing type 1 or type 2 diabetes, or gestational diabetes diagnosed during pregnancy. Gestational diabetes screening involves a glucose challenge test between 24-28 weeks of pregnancy, or earlier for those at high risk. Treatment involves lifestyle changes like diet and exercise, and may require insulin if needed to control blood glucose levels. After delivery, women with gestational diabetes have increased risk of developing type 2 diabetes and should undergo testing to check for prediabetes or diabetes.

1. Gestational Diabetes
Dr. Usama Ragab Youssif
Lecturer of Internal Medicine
Zagazig University

2. Diabetes in Pregnancy: 2 Categories
Pregestational diabetes Gestational diabetes
Pregnancy in
pre-existing diabetes
• Type 1 diabetes
• Type 2 diabetes
Diabetes diagnosed in
pregnancy
2018 Diabetes Canada CPG – Chapter 36. Diabetes and Pregnancy

3. Definition
• For many years, GDM was defined as any degree of glucose
intolerance that was first recognized during pregnancy, regardless of
the degree of hyperglycemia.
• This definition facilitated a uniform strategy for detection and
classification of GDM, but this definition has serious limitations.

4. Limitations
• GDM may be undiagnosed preexisting diabetes
• It is not considering severity of dysglycemia
• We are expecting many cases of undiagnosed preexisting diabetes

5. Alarm for early screening of Diabetes
• In individuals with risk factors or in high-risk populations
• This may diagnose those with preexisting diabetes results in better
outcome
• Selective screening vs universal early screening before 15 weeks

6. Criteria for
screening for
diabetes or
prediabetes in
asymptomatic
adults

7. PERSONAL USE ONLY
Universal screening for GDM
@ 24-28 weeks gestational age
Screen earlier if risk factors for GDM
(see next slide)
2018 Diabetes Canada CPG – Chapter 36. Diabetes and Pregnancy
Gestational Diabetes (GDM)
Screening

8. PERSONAL USE ONLY
Early Screening for Women at High Risk
for Type 2 Diabetes
2018 Diabetes Canada CPG – Chapter 36. Diabetes and Pregnancy
Women at high risk of type 2 diabetes
Screen with A1C (or FPG if A1C unreliable)
in first trimester
A1C ≥6.5% or FPG ≥7.0 mmol/L  treat like
type 2 diabetes
Confirm diagnosis post-partum
FPG, fasting plasma glucose

9. High-risk groups
Most women with GDM are detected on routine screening at 24–28 weeks,
but certain high-risk groups should be screened earlier. These risk factors
include:
• Previous GDM.
• A large baby in their last pregnancy, e.g., >4.5kg.
• Maternal obesity (BMI above 30kg/m2).
• Family history of diabetes (1st-degree relatives).
• Minority ethnic family origin with a high prevalence of diabetes.
Consider a diagnosis of MODY or T1DM in women who have GDM with no
classic risk factors (many women with MODY have a history of GDM).

10. Burden
• Hyperglycemia during pregnancy occurs in up to 10–13% of women
• Pregnancy induces a state of IR, with ↑ levels of GH, progesterone,
placental lactogen, and cortisol all contributing to IGT.
• It is associated with ↑ risk of subsequent T2DM in up to 50% (may be
reduced by diet, lifestyle and breastfeeding for 6 month and by
metformin).

11. Recommendations
–
ADA
2023
2.26a In individuals who are planning pregnancy, screen
those with risk factors B and consider testing all individuals
of childbearing potential for undiagnosed diabetes. E
2.26b Before 15 weeks of gestation, test individuals with risk
factors B and consider testing all individuals E for
undiagnosed diabetes at the first prenatal visit using
standard diagnostic criteria if not screened preconception.
2.26c Individuals of childbearing potential identified as
having diabetes should be treated as such. A

12. Recommendations
– ADA 2023
• 2.27 Screen for gestational
diabetes mellitus at 24–28
weeks of gestation in pregnant
individuals not previously found
to have diabetes or high-risk
abnormal glucose metabolism
detected earlier in the current
pregnancy. A

13. Screening of
GDM
1. The “one-step” 75-g OGTT derived from
the IADPSG criteria, or
2. The older “two-step” approach with a 50-g
(non-fasting) screen followed by a 100-g
OGTT for those who screen positive based
on the work of Carpenter-Coustan’s
interpretation of the older O’Sullivan and
Mahan criteria.

14. One-step Strategy

15. Two-step Strategy

16. PERSONAL USE ONLY
Why Diagnose and Treat GDM?
• Macrosomia
• Shoulder dystocia and
nerve injury
• Neonatal
hypoglycemia
• Preterm delivery
• Hyperbilirubinemia
• Caesarian section
• Offspring obesity
• Offspring diabetes
2018 Diabetes Canada CPG – Chapter 36. Diabetes and Pregnancy

17. GDM
treatment
recommendations
15.14 Lifestyle behavior change is an essential
component of management of gestational
diabetes mellitus and may suffice as treatment
for many individuals. Insulin should be added if
needed to achieve glycemic targets. A
15.15 Insulin is the preferred medication for
treating hyperglycemia in gestational diabetes
mellitus. Metformin and glyburide should not be
used as first-line agents, as both cross the
placenta to the fetus. A Other oral and
noninsulin injectable glucose-lowering
medications lack long-term safety data.

18. GDM treatment
recommendations

19. Insulin
Therapy in
GDM
Required in 10–20% of GDM pregnancies
Used in conjunction with diet and exercise or in
addition to metformin.
Regimen should be tailored to glycemic profile
and patient acceptability: boluses alone, basal
alone, mixed or basal bolus.
Most (but not all) women can stop insulin
and/or oral hypoglycemic treatments
immediately after birth.

20. Targets recommended by the Fifth International
Workshop-Conference on Gestational Diabetes
Mellitus
Fasting glucose <95
mg/dL (5.3 mmol/L)
and either
One-hour
postprandial
glucose <140 mg/dL
(7.8 mmol/L) or
Two-hour
postprandial
glucose <120 mg/dL
(6.7 mmol/L)

21. GDM: Glycemic Management During
Labour and Delivery
• Keep maternal blood glucose between 4.0
and 7.0 mmol/L  reduce risk of neonatal
hypoglycemia
2018 Diabetes Canada CPG – Chapter 36. Diabetes and Pregnancy

22. Post-
partum
follow-up

23. GDM: Postpartum Management
1. Encourage Breastfeeding
• Reduce neonatal hypoglycemia, childhood obesity &
diabetes, AND maternal risk of diabetes & hypertension
2. 75 g OGTT between 6 weeks - 6 months
postpartum to detect prediabetes or diabetes.
Suggest phone calls/email reminders to improve
testing rates
2018 Diabetes Canada CPG – Chapter 36. Diabetes and Pregnancy

24. PERSONAL USE ONLY
GDM: Postpartum OGTT
75 g oral glucose tolerance test
• 6 weeks to 6 months
• If diagnosed with diabetes early in pregnancy,
do FPG or OGTT at 6-8 weeks postpartum
Normal
Healthy
behaviour
interventions
Impaired glucose
tolerance
Healthy behaviour
interventions +/-
metformin
2018 Diabetes Canada CPG – Chapter 36. Diabetes and Pregnancy
Type 2
diabetes
Healthy behaviour
interventions +/-
metformin +/- insulin
FPG, fasting plasma glucose; OGTT, oral glucose tolerance test

25. Checklist for gestational diabetes during clinic
visit
• Monitoring blood glucose, aim:
Fasting blood glucose <5.3mmol/L.
1h postprandial blood glucose <7.8mmol/L (some advocate lower
blood glucose targets for obese women e.g., <5.1 fasting and <7.0
after meals).
• Monitor maternal weight, bP, and urinalysis.
• Monitor fetal size (abdominal circumference).

26. Checklist for gestational diabetes during clinic
visit
Treatment:
• Diet and lifestyle advice.
• Metformin if diet and exercise inadequate
• Insulin—NPH and/or rapid-acting insulin analogues (aspart and
lispro).
Reinforce dietary advice throughout pregnancy.
Advice on physical activity (at least 30min daily).

27. Checklist for gestational diabetes during clinic
visit
• At 36 weeks’ clinic visit, discuss and document:
Mode and timing of delivery.
blood glucose management plan for delivery.
Increased risk of T2DM and evidence for delaying and prevention
(diet and lifestyle, breasfeeding, metformin).
benefits of breastfeeding (mother and baby).
Options for safe, effective post-partum contraception.
• Post-partum follow-up—fasting glucose or OGTT 6 weeks post-
delivery.

28. Thanks