Gestational Diabetes Mellitus: Diabetes In A Pregnant Woman, Risk Factors, Diagnosis, Treatment

Gestational diabetes is diabetes diagnosed for the first time during pregnancy (gestation). During pregnancy, there is a state of insulin resistance and elevated insulin levels, which might lead to diabetes in pregnant women.


By Dr. Vimal Grover Last Updated:

Gestational Diabetes Mellitus: Diabetes In A Pregnant Woman, Risk Factors, Diagnosis, Treatment

High blood sugar during pregnancy affects between  2 per cent to 5 per cent of pregnant women. During pregnancy, there is a state of insulin resistance and elevated insulin levels, which might lead to diabetes in pregnant women.

Gestational Diabetes Mellitus (GDM) is defined as glucose intolerance that was not present or recognised prior to pregnancy. The amount of GDM varies in different countries in direct proportion to the commonness of type II diabetes. India being the diabetic capital of the world, the incidence of GDM is higher than in the USA or UK.

Risk factors for GDM

Gestational Diabetes Mellitus

Here are a few factors that increase a pregnant woman's risk of developing GDM:

1) Previous history of big baby (body weight > 4kg).
2) Being a member of an ethnic group with a high role of type II diabetes.
3) Polycystic ovary syndrome.
4) High blood pressure.
5) Previous history of spontaneous abortion and unexplained pregnancy loss.Strong family history of diabetes.
6) Age more than 35 years.
7) A modifiable known risk factor is obesity.
8) In addition to lack of exercise, dietary fat and lifestyle habits that adversely influence insulin resistance such as smoking and certain drugs would have an important influence.

Screening and diagnosis of GDM

Gestational Diabetes Mellitus

1) As recommended by the ACOG (American Congress of Obstetricians and Gynecologists), most centres worldwide practice universal screening for detection of pregnancy diabetes as the most sensitive and practical approach.

2) When the universal screening approach is employed with no known risk factors, the patient should undergo 1 hour glucose test in 24-28 weeks of gestation.

3) Patients with known risk factors may be tested at the onset of prenatal care.

4) Abnormal results for the 1-hour screening tests will occur in 15 per cent of patients. These will require further confirmation with a 100gm glucose tolerance test, with blood drawn at 1 hr, 2 hr and 3 hrs.

5) Patients with GDM have a high chance of having a big baby with a body weight > 4kg, premature delivery, difficult delivery, high BP, increased incidence of C-section, and breathing difficulties.

Management and treatment of GDM


Gestational Diabetes Mellitus

1) Diet is the main step of treatment in GDM even if insulin or oral tablets are required, and it is the cornerstone of management in glycemic control (blood sugar (glucose) level in a person with diabetes mellitus).
2) Blood glucose levels should be monitored up to 4 times a day, fasting level and 2 hours after each meal.
3) The target is to keep fasting blood sugar between 70 mg-90 mg/dl (diabetes levels).
4) The post-meal goal is ideally below 120 mg/dl.
5) The upper limit acceptable is 135 -140 mg/dl.
6) A quality nutritional diet is essential, and the calorie intake is based on ideal body weight. Recommendations are 30 kcal/kg for patients with a BMI of 22-25, 24 kcal/kg for BMI of 26-29 and 12-15, 24 kcal/kg for women with a BMI>30.
7) It is recommended that obese women (body mass index more than 30kg/m²) should be allowed a relatively small gain of weight during pregnancy of 7kg and a proportionately greater weight gain for underweight women at the onset of pregnancy.
8) The recommendation of overall dietary ratio is 33-40 per cent of complex carbohydrates, 35-40 per cent fat and 20 per cent protein. This will help 75-80 per cent of GDM.
9) The calories may be distributed 10-20 per cent at breakfast, 20-30 per cent at lunch and 30-40 per cent at dinner and 30 per cent with snacks especially, a bedtime snack in order to reduce night hypoglycemia.
10) Calorie restriction however should be approached with caution and under medical supervision, and a qualified dietician with a personalised nutrition plan based on the height and weight of the pregnant woman.



1) Research has shown that the most physically active women have the lowest prevalence of GDM.
2) Good physical activity during early pregnancy may reduce the risk of developing GDM.
3) Daily self-glucose monitoring with only test strips and a glucometer appears to be useful in pregnancy complications.

Insulin and oral tablets:


Some women suffering from GDM cannot be managed with diet and exercise to achieve desired blood sugar levels. So, to avoid complications for the baby and the mother due to high blood sugar and woman needs to take insulin. So, the remaining 20 per cent GDM women will require insulin (human insulin is the best), which should be initiated early to prevent chances of big baby. It is recommended that the diet should be maintained before starting insulin for at least 2 weeks to see the benefits of diet modification.

However, when GDM is diagnosed after 30 weeks and a short time is available to lower blood sugar, then insulin should be started early. Regular insulin, which is often used in pregnancy has certain drawbacks. It starts its action 30-60 min after injection and achieves control after 2-3 hours. In addition, the effect lasts too long (duration of 8-10 hours) with an increased risk of low blood sugar levels.

Almost all types of use of insulin show no differences in the rate of caesarean section, preterm delivery (premature birth), pre-eclampsia (a dangerous complication due to high blood pressure) or complication to the newborn. So, at present human NPH (Neutral Protamine Hagedorn) insulin is considered to be the safest, but has to be given at least 2-3 times a day.

Conventionally, there are 2 methods for giving insulin: subcutaneous multiple injections or continuous subcutaneous insulin infusion pumps. Traditionally, insulin therapy has been considered the gold standard for the management of GDM because it is effective and safe.

Since GDM is characterised by insulin resistance, treatment with oral blood sugar-lowering drugs is of potential interest. However, the American college of obstetrician and gynecologists and ADA (American Diabetes Association) do not currently recommend oral tablets. Metformin tab is currently approved by the USFDA (US Food and Drug Administration) in the treatment of type II diabetes, and it has been suggested that the drug represents an ideal drug for primary prevention in the study in GDM.

In some studies, tablets like metformin and glyburide have also been used safely to keep sugar under control. Exercise has been shown to improve sugar control as it increases tissue sensitivity to insulin. Exercising 3 or more times per week for at least 10-15 minutes is the typical recommendation.

Patients are usually scheduled for follow-up visits every 1-2 weeks throughout pregnancy. HbA1C (Glycated haemoglobin) is done every 3 months to check overall diabetic control. Urine infection and kidney function are also checked. Ultrasound is done more frequently for fatal growth and well-being. If blood glucose levels are normal and there are no other complications, it is ideal for the mother to deliver at term. Pregnancies complicated by GDM should not go beyond term. In complicated cases, a caesarean is recommended.

We hope that this article might of some help to you. We would like to wish you a healthy, happy and safe pregnancy!