GDM - Gestational diabetes mellitus (GDM) is a condition in which a hormone made by the placenta prevents the body from using insulin effectively. Glucose builds up in the blood instead of being absorbed by the cells.

1. Gestational
Diabetes Mellitus
INTRODUCTION
SUMI SINGH
NEPAL MEDICAL COLLEGE AND TEACHING HOSPITAL

2. Definition
• Gestational Diabetes Mellitus (GDM) is defined as carbohydrate
intolerance of variable severity with onset or first recognition
during the present pregnancy
• These cases are basically pre-existing type 2 diabetes.
• It appears that many of these women diagnosed as GDM, are already
suffering from impaired b-cell function but remained undetected.
• Majority of these women (>50%) with GDM ultimately develop overt
diabetes by next 15 to 20 years.

3. Risk Factors for GDM
(a) Positive family history of diabetes
(b) Having a previous birth of an overweight baby of 4 kg or more
(c) Previous stillbirth with pancreatic islet hyperplasia revealed on autopsy
(d) Unexplained perinatal loss
(e) Presence of polyhydramnios or recurrent vaginal candidiasis
(f ) Persistent glycosuria
(g) Age over 30 years
(h) Obesity

4. SCREENING
Screening strategy for detection of GDM are:
• Low risk—Absence of any risk factors as mentioned above → blood
glucose testing is not routinely required
• Average risk—Some risk factors → perform screening test
• High risk—Blood glucose test as soon as feasible.

5. The method employed is by using 50 gm oral glucose challenge test without
regard to time of day or last meal, between 24 weeks and 28 weeks of
pregnancy.
A plasma glucose value of 140 mg% or that of whole blood of 130 mg% at 1
hour is considered as cut off point for consideration of a 100 gm (WHO– 75
gm) glucose tolerance test.

6. Two or more of the venous plasma concentrations must be met or exceeded
for a positive diagnosis. The test should be done in the morning after an
overnight fast of between 8 and 14 h and after at least 3 days of
unrestricted diet (≥150 g carbohydrate per day) and unlimited physical
activity. The subject should remain seated and should not smoke
throughout the test.`1
1. Diagnosis and Classification of Diabetes Mellitus, American Diabetes
Association,Diabetes Care 2004 Jan; 27(suppl 1): s5-
s10.https://doi.org/10.2337/diacare.27.2007.S5

8. DiPSi (Diabetes in Pregnancy Societies of india): recommends 1-step
procedure with 75 gm oral glucose without regard to the time of the
last meal. A venous plasma glucose value at 2-hour more than 140
mg/dl is diagnosed GDM.

9. HAZARDS:
(1) Increased perinatal loss is associated with fasting hyperglycemia.
Fetal anomalies are however not increased.
(2) Increased incidence of macrosomia
(3) Polyhydramnios
(4) Birth trauma
(5) Recurrence of GDM in subsequent pregnancies is about 50%.