Gestational diabetes Mellitus is defined as: “Glucose intolerance of any severity with onset or first recognition during pregnancy” This definition is applicable irrespective of whether the condition resolves after delivery or not. It does not exclude the possibility that diabetes could have antedated pregnancy.

1. Gestational Diabetes Mellitus
Yashaswi
Junior Resident
Dept of Medicine

2. Definition
Gestational diabetes Mellitus is defined as:
• “Glucose intolerance of any severity with onset or
first recognition during pregnancy”
• This definition is applicable irrespective of whether
the condition resolves after delivery or not.
• It does not exclude the possibility that diabetes
could have antedated pregnancy.

3. Epidemiology
• Global prevalence rates vary from 1% to >15%.
• The prevalence of GDM is steadily rising in India.
• Asians are considered to be high risk ethnic group
for GDM.
• The prevalence of GDM in India is >15%.
• The prevalence is higher among the urban
population as compared to rural population

4. Pathophysiology
Early pregnancy:
• Main hormones involved are estrogen and
progesterone.
• These hormones cause hyperinsulinemia by promoting
beta cell hyperplasia and increased insulin release.
• Insulin sensitivity: normal or increased.
• This leads to low plasma glucose levels till around 20th
week of pregnancy.

5. Late Pregnancy:
• After 20 weeks of gestation, the placental hormones
start playing an important role in development of
insulin resistance.
• Main placental hormone: Human placental lactogen.
• Other hormones: prolactin, cortisol, progesterone
• All these hormones antagonise the effect of insulin
and bring about a state of physiological insulin
resistance.

6. Reason for development of physiological insulin
resistance in later pregnancy:
• Facilitated diffusion following a meal: Higher blood
glucose levels enable free diffusion to fetus to meet its
increased demands
• Accelerated starvation during fasting state: Higher
levels of FFAs and Ketone bodies to provide energy to
mother during starvation.

7. Risk Factors for GDM
• Age >25years
• Obesity (BMI>25kg/m2)
• Waist circumference >80 cm
• Diabetes in first degree relative
• Previous history of GDM or Glucose intolerance
• Previous h/o macrosomic baby
• Members of high risk ethnic groups
• Polycystic Ovarian Syndrome
• Previous h/o Polyhydraminos
• Previous unexplained perinatal loss or birth of
malformed infant

8. Complications of GDM
Maternal Complications:
• Pre-eclampsia
• Polyhydraminos
• Higher chances of operative or assisted delivery
• Perineal Tear
• Risk of future diabetes

9. Fetal Complications:
• Fetal Macrosomia
• Birth trauma- shoulder dystocia, clavicle fracture,
brachial palsy
• Prematurity
• Respiratory Distress Syndrome
• Metabolic complications: hypoglycemia,
hyperbilirubinemia, hypocalcemia, polycythemia
• Obesity and Diabetes in later life

10. Pre-existing Diabetes in Pregnancy
Congenital malformations are more common in pre-
existing Diabetes than in GDM.
Congenital Malformations
CNS:
Neural tube defects
Caudal regression syndrome
Holoprosencephaly
CVS:
Tetralogy of Fallot
Transposition of Great Arteries
Left sided obstructive lesions

11. Genitourinary System
• Renal Agenesis
• Hydronephrosis
• Ureteral Duplication
Gastrointestinal System
• Duodenal and anorectal atresia

12. Maternal Complications:
Retinopathy: can worsen during pregnancy
Improvement of glycemic before or during pregnancy can
paradoxically worsen retinopathy
Nephropathy: in women with reduced creatinine
clearance, there is higher risk of worsening of
retinopathy
It is associated with:
• Increased risk of maternal hypertensive complications
• Increased risk of preterm delivery
• Increased risk of fetal growth restriction and fetal
distress

13. Screening for GDM
ADA recommendation: All women at high risk for GDM
should be screened.
Since, South east Asians are a high risk ethnic group,
universal screening of GDM is recommended for all Indian
women.
When to screen:
ADA: As early as possible. If negative repeat test at 24-28
weeks
DIPSI: First screening test at first antenatal visit. If negative,
repeat at 24-28 weeks and then again at 32-34 weeks.

14. IADPSG Guidelines
To be performed at first antenatal visit
FPG, HbA1c and random glucose levels are used.
If:
• FPG≥126mg/dl,
• HbA1c≥6.5%
• Random glucose≥200mg/dl with symptoms of
hypergylcemia, diagnose as overt DM.
FPG 92-125mg/dl- GDM
FPG<92mg/dl- repeat screening at 24-28 weeks

15. At 24-28 weeks:
75gm fasting Oral Glucose Tolerance Test is used
for screening for GDM
FPG≥126mg/dl- Overt Diabetes Mellitus
FPG<126mg/dl:
Fasting 1 hour 2 hour
Plasma Glucose
(mg/dl)
≥92 ≥180 ≥153

16. DIPSI Guidelines
• 75gm oral glucose load is given irrespective of
fasting state of the patient.
• Sample collected after 2 hours.
• A value of ≥140mg/dl is considered diagnostic of
GDM.
• In resource limited setting , 75g DIPSI criteria can
be considered for screening of pregnant women for
GDM

17. Oral Glucose Tolerance Test
• Test preceded by ≥3 days of normal, unrestricted diet.
• Carbohydrate rich diet (30-50gm) on night before test.
• Overnight fast of 8-14 hours is advised, water may be
ingested.
• Collect fasting (and all other samples) in sodium
flouride tubes.
• Timing of test (0 hours) starts at beginning of glucose
drink
• Adult ingest 75g of anhydrous glucose in 250-300ml
water over 5 minutes.
• Take blood sample at 1 and 2 hours.

18. Management
Medical Nutrition Therapy
Cornerstone of GDM management
Some women will be able to manage the glucose levels
effectively with MNT alone
Aims:
• Fulfill minimal nutritional recommendation for
pregnancy
• Achieve glycemic goals without weight loss or undue
weight gain
• Avoid ketonemia/ketonuria from calorie
restriction/starvation

19. • Small frequent meals (once in 2-3hours) are ideal to
avoid hypoglycemia.
• Avoid prolonged fasting.
• Bedtime snack is advisable to avoid development of
ketosis at night.
Physical Activity:
• Physical Activity of 30-45min/day is recommended.
• Break up extended periods of sedentariness.
• Activities that increase blood pressure should be
avoided (e.g.: lifting heavy weights, pushing heavy
objects).

20. Body weight BMI (kg/m2) Recommend
Weight Gain
(kg)
Underweight <18 11-13.5
Ideal Body
Weight
18-24 8-11
Overweight 24-30 5.5-8
Obese 30-35 3.5-5.5
Morbidly Obese >35 <3.5
Recommended Weight Gain in Diabetic pregnancies

21. Diet
Total Calories
Required
1st Trimester: 30-32kcal/kg
2nd and 3rd Trimester: 38kcal/kg
Carbohydrate 50-55% of calories
Fat <30% of Calories
Protein 1.1g/kg
Fibre 20-40g/day

22. Glycemic Target in Pregnancy
Fasting
(mg/dl)
1 hour
(mg/dl)
2 hour
(mg/dl)
ADA ≤95 ≤140 ≤120
DIPSI ≤90 - ≤120

23. Insulin Therapy
Insulin therapy is recommended if MN fails to achieve
glycemic target by 1-2 weeks.
Consider insulin therapy at the time of diagnosis if
glucose levels are high:
Fasting>120mg/dl
Postprandial>200mg/dl..
Insulin therapy has to be individualized.
Postprandial glucose values need special attention in
diabetic women.

24. • Start with low dose (4-10 U per day) depending on
blood glucose levels.
• Titrate frequently till target levels are achieved.
• Dosage of insulin normally increases as pregnancy
advances.
• If fasting glucose levels are increased, basal insulin
ate bedtime is advised.
• If postprandial levels are high, short acting insulin is
added before meals.

25. Short acting insulin: regular insulin, insulin lispro,
insulin aspart are considered safe during pregnancy
Long acting analogues: Insulin detemir is approved
for use in pregnancy.
Insulin glargine and degludec are currently not
recommended in pregnancy.
Premixed insulin is not the ideal type of insulin for
pregnancy since it compromises flexibility.
Insulin in preexisting diabetes:
Insulin requirements fall during first trimester and
gradually rises thereafter.

26. Oral Antidiabetic Agents
Oral Antidiabetic agents were traditionally considered to be
contraindicated in pregnancy.
Metformin, Glibeclamide, Acarbose- FDA category B drugs.
Metformin:
• No serious adverse events with metformin
• No significant difference in outcome between insulin and
metformin.
• Possible concerns: Significant placental transfer, neonatal
hypoglycemia.

27. Glibenclamide:
• Does not cross placental barrier hence fetal exposure is
minimal.
• No significant difference between groups with respect to
macrosomia, lung complications, hypoglycemia or fetal
anomalies.
• In some studies, glibenclamide is associated with a higher
risk of adverse outcomes therefore its use is not
recommended.

28. SMBG Monitoring
All women with diabetes during pregnancy should
preferably do SMBG daily.
Indications for more frequent monitoring:
• Uncontrolled diabetes
• Fluctuating blood glucose
• Changing insulin doses
• Hypoglycemia
• Multiple daily insulin injections

29. Obstetric Management
Antenatal visits:
Till 28 weeks: once a month
28-36 weeks: once in two weeks
36 weeks to delivery: weekly
Early pregnancy scan (7-8 weeks): for dating and
viability.
11-13 weeks scan: Can pick up 60% of structural
anomalies
18-20 weeks :targeted anomaly scan

30. Serial Growth Scan is done every 4 weeks from 28th to
36th weeks to determine fetal growth anomalies.
Timing of Delivery:
• In women on insulin delivery is usually planned at
38 weeks.
• In diet controlled diabetes without macrosomia,
delivery aimed at 40 weeks
Mode of delivery:
• Vaginal delivery is safe in GDM
• No contraindications to vaginal delivery
• LSCS only for obstetric indications

31. Postpartum Assessment
• In most cases of GDM, diabetes resolves after delivery.
• Insulin requirements usually come down
completely/reduce significantly.
• However, it can persist in 5 to 10% of cases.
• All women with GDM should undergo 75g OGTT 6
weeks after delivery to classify the glycemic status.
• Abnormal test results identify women at high risk of
developing diabetes over next 5-10 years.

32. Risk Factors for Progression to Diabetes
• Overweight/Obesity
• Member of high-risk ethnic group
• Family history of Diabetes
• GDM diagnosed in first trimester
• Need for insulin during pregnancy
• Persistent IGT following delivery

33. Thank you

34. Multiple Choice Questions

35. At what glucose level is insulin secretion stimulated?
A. >60mg/dl
B. >70mg/dl
C. >80mg/dl
D.>100mg/dl
Answer:
B. >70mg/dl

36. The weight of the monofilament used to test diabetic
neuropathy?
A. 5 gm
B. 10 gm
C. 15gm
D.2.5gm
Answer:
B. 10 gm

37. Which of the following is a peakless insulin?
A. Insulin lispro
B. NPH insulin
C. Insulin aspart
D.Insulin detemir
D. Insulin Detemir

38. Target FPG level in GDM patients according to DIPSI
guidelines
A. 80mg/dl
B. 90mg/dl
C. 95mg/dl
D.100mg/dl
A. 90mg/dl

39. Which three of the following statements are true?
Women with gestational diabetes:
A Have insulin secretory defects
B Have a higher risk of developing type 2 diabetes
C Have a higher risk of developing type 1 diabetes
D Should be screened for retinopathy in pregnancy
A Have insulin secretory defects
B Have a higher risk of developing type 2 diabetes

40. Which of the following is false?
A. The concordance rate in identical twins in T2DM is
40-60%
B. The concordance rate in identical twins in T2DM is
70-90%
C. If both parents have T2DM the risk is 40%
D.The concordance rate in identical twins in T1DM is 40-
60%
A. The concordance rate in identical twins in T2DM is
40-60%

41. Iron deficiency anemia results in:
A. Falsely high HbA1c
B. Falsely low HbA1c
C. No effect on HbA1c
D.Variable effect on HbA1c
A. Falsely high HbA1c