GDM AKA Gestational Diabetes Mellitus

March 2, 2020 by admin0

Many women have diabetes during pregnancy, why?

GDM is defined as any degree of glucose intolerance with onset or first recognition during pregnancy

It includes the situation where it is diagnosed for the first time in the current pregnancy even if the glucose intolerance was preexistent or begun concomitantly with the pregnancy.

Gestational diabetes mellitus (GDM) has become one of the most common medical complications of pregnancy. It can have significant health implications for both the mother and child.

Maternal carbohydrate metabolism is where it starts to change during pregnancy. As pregnancy advances insulin resistance increases due to placental hormones. If there is inadequate secretion of insulin in response to increased bloodsugar, then one develops GDM.

The first screening for GDM starts at the first booking visit. This is done by checking fasting blood glucose or timed glucose level measurement and again rechecking once more at 24–28 weeks of gestation, usually with a 75gm OGTT. This protocol of monitoring is for pregnant women with low risk. The protocol for Patients with High risk of developing GDM in the current pregnancy, is to screen them twice, both in the booking visit and later at 24-28 weeks of pregnancy with the 75gm GTT.

  • High risk women are those who have a BMI of greater than 30 kg/m2.
  • H/O of GDM in previous pregnancies or fetal macrosomia.
  • family history of diabetes mellitus.
  • glucose detected on urine dipstick testing (2+ or above on one occasion, or 1+ on two or more occasions).



Management of GDM is by using a multidisciplinary approach involving a team comprising of an obstetrician, endocrinologist and dietician. Most of the patients are initially started on and controlled through diet changes, but as pregnancy advances if the insulin resistance increases some may require pharmacologic therapy with tablets or insulin injections to prevent complications.

What are the implications on the fetus and new born, before and after birth?

GDM if uncontrolled can adversely affect the intrauterine development of fetus at each trimester.

In the first trimester, Spontaneous miscarriages and major congenital anomalies may be induced.This is usually so if the diabetes is overt.

During the second and third trimesters, Fetal macrosomia (abnormal Increased fetal growth in size) sudden intrauterine demise, may occur if  sugars are uncontrolled.

Postbirth there is increased chance of neonatal hypoglycaemia, jaundice and polycythaemia in the baby.


Long-term medical considerations of GDM:

GDM disappears in 95 % of women post-delivery. But are the risk of developing diabetes at the rate of 20% to 60% in future and increased risk of developing GDM in subsequent pregnancies.

75 gm GTT (2step) should be performed at least 6 weeks after delivery if both glucose levels and GTT are normal post-partum, lifestyle modification and Thereafter, annual glucose and HbA1C testing can detect deteriorating glycemic control and predict the onset of Type 2 DM.

All patients with prior GDM should seriously consider lifestyle modifications, good physical activity and diet modifications that will lessen insulin resistance and prevent or at least delay the age of onset of DM in future.

If GTT is impaired intense lifestyle modification and  regular monitoring of blood glucose levels 3-6monthly is advised.

If overt diabetic status is diagnosed during pregnancy then DM protocol of management to be followed.

GDM carries a small but potentially important longer-term risk of obesity and glucose intolerance in children too.

Families should be encouraged to help children adopt lifestyles that reduce the risk of obesity.


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An experienced gynecologist for normal delivery in Bangalore and she is a member of Bangalore Society of Obstetrics & Gynecological and FOGSI.

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