What is gestational diabetes?
Gestational diabetes is diagnosed in a pregnant woman with no history of any kind of diabetes in her life. Like the general form, the gestational type is characterized by abnormally high blood glucose levels . High glucose levels in the blood can be dangerous both for the mother and child. Gestational diabetes is usually diagnosed later in pregnancy; so, if you have diabetes in the first trimester that often means you have had it before getting pregnant .
Gestational Diabetes Classification
- Gestational diabetes mellitus or GDM (common) 
- Gestational diabetes insipidus or GDI (rare) 
What causes diabetes during pregnancy?
Researches are still being carried out to find the exact factors triggering high blood glucose levels in pregnancy. But, the hormonal and other changes occurring in your body are known to be responsible for the problem. Certain genetic factors have also been recognized to play a role in some cases .
Pathophysiology of Gestational Diabetes Mellitus
The body changes during pregnancy make your body somewhat resistant to insulin . Insulin is a hormone produced by the pancreas to help your body use glucose for producing energy. The reduced functioning of insulin during pregnancy causes glucose build up in the blood, leading to diabetes. Gestational diabetes is more likely to occur late in the second trimester or during the third trimester as the pregnancy hormone levels gradually becomes higher with the advancement of your pregnancy .
What are the risk factors for gestational diabetes?
- Being overweight before conceiving
- Being over 25 years of age 
- History of gestational diabetes in a previous pregnancy
- Family history of type 2 diabetes
- Carrying twins
- A tendency to have high blood glucose levels, but not high enough to be diagnosed as diabetes (pre-diabetes) 
- Polyhydramnios (extremely high amniotic fluid levels)
- Having given birth to a baby weighing over 9 pounds 
- History of miscarriage or stillbirth in a previous pregnancy
- Having high blood pressure
- Having a hormonal disorder named polycystic ovary syndrome (PCOS) 
- Belonging to certain high risk ethnic groups including Native American, Black, Asian and Hispanic
What are the signs and symptoms of gestational diabetes?
It does not cause any detectable signs in most women , but some may experience the following symptoms:
- Increased urination
- Excessive hunger and thirst 
When to call the doctor?
Watch out for the following symptoms as they may indicate some serious complications:
- Extreme fatigue
- Dizziness and confusion
- Excessive sweating 
- Losing consciousness
- Severe headaches
- Joint pain
- Breathing very fast/having fruity breath 
- Severe nausea and vomiting or diarrhea continuing for over 6 hours
How to prevent gestational diabetes?
Seeking medical advice as soon as you plan to have a baby can help to reduce the chances of GDM. Your doctor can evaluate your risks for developing the condition and help you to maintain a healthy blood glucose level, preventing the condition .Here are a few measures to keep gestational diabetes away:
- Monitoring your blood sugar levels from at least 3 months prior to getting pregnant 
- Reaching and maintaining a healthy weight before conceiving
- Following your doctor’s advice regarding healthy weight gain in pregnancy
- Avoiding medicines that may lower your insulin resistance (such as prednisone) 
- Following a regular exercise schedule before and during pregnancy 
- Practicing relaxation techniques and prenatal yoga to manage stress
Gestational Diabetes Tests and Diagnosis
Screening for GDM is usually performed between the 24th and 28th weeks while High risk women are screened quite early in their pregnancy .
Glucose challenge test (type A1): Involves measuring your blood glucose levels about one hour after taking a glucose drink. Blood sugar levels higher than 130 to 140 milligrams/deciliter only indicates borderline (high risk) diabetes, calling for further testing. GCT has a significant false positive rate with 15%-20% women getting positive results; although, only 2%-5% of them actually develops GDM .
Several diagnostic criteria are used for confirming GDM. Here are the criteria proposed by O’Sullivan and Mahan in 1964 .
Glucose tolerance testing (type A2): You will be asked to fast overnight for the test and will be given a 75gm glucose drink once the fasting readings are taken. Having two or more of the following four abnormal readings confirms the diagnosis :
|Time spent after taking the glucose drink||Blood glucose levels|
|1 hour||165 mg/dL|
|2 hours||143 mg/dL|
|3 hours||125 mg/dL|
A positive diagnosis of GDM is followed by certain tests for monitoring your health and checking the wellbeing of your baby. These include:
- Frequent blood tests (usually once before a meal and an hour after a meal) for monitoring your blood glucose levels 
- Ultrasound Exams between the 18th and 20th week to monitor the heart and after the 28th week to check your baby’s size and growth 
- Nonstress test to check that the baby is getting enough oxygen
- Biophysical profile (BPP) – a combination of an ultrasound and non-stress test 
- Fetal movement counting or kick counting to calculate the time between two movements 
- Ketone test – a type of urine test to make sure that the baby is getting enough nutrition 
Gestational Diabetes Treatment
Contact your dietician to make a diet plan determining the exact amount of carbohydrates, protein and fat you need every day . Make sure to increase your daily intake of high-fiber foods like fresh vegetables and fruits, cereals, whole grain breads and legumes as their absorption takes longer than that of simple carbohydrates, keeping your blood sugar levels in control .
Exercise and Physical Activity
Following a light exercise routine 4-5 times a week helps to deal with high blood glucose levels by allowing your body use insulin efficiently. Make sure to consult your health care provider regarding what exercises are safe for you .
Managing GDM with Medication
In some rare cases (around 10%) , insulin shots may be recommended for maintaining the blood sugar levels to protect the baby. Insulin usually does not cause any serious side effects in the baby. Blood sugar medications are usually not recommended in pregnancy. However, the oral antidiabetic drug Glyburide is currently being considered as a possible treatment option as the amount that passes through the placental barrier has been shown to be too little to harm the baby .
Delivering the Baby
Inducing labor may be recommended in severe cases to prevent the baby from getting too big in size due to the extra glucose . A cesarean section may be recommended for women with large babies.
Postpartum care is often not necessary as the diabetes goes away on its own a few weeks after delivery .
Herbal and alternative medicines used to treat diabetes (e.g. cinnamon and fenugreek) are generally not recommended during pregnancy.
What are the risks of gestational diabetes?
- High blood pressure and preeclampsia 
- Increased chances of a cesarean delivery 
- Increased risk of gestational diabetes in a future pregnancy and type 2 diabetes as you get older
- Preterm labor and birth
Risks to the baby
- Higher than normal birth weight
- Respiratory distress syndrome (due to premature birth) 
- Low blood sugar or hypoglycemia due to abnormally high insulin production 
- Various birth defects
- Increased risk of type 2 diabetes and obesity in future
How common is gestational diabetes?
Incidence statistics show around 135,000 women develop gestational diabetes in the US every year .
Gestational Diabetes Support Group
American Diabetes Association
ATTN: Center for Information
1701 North Beauregard Street
Alexandria, VA 22311
Gestational Diabetes ICD-9 and ICD-10 Codes
The ICD-9 code used for GDM is 648.8  while its ICD-10 code is O24 [ref]
- http://apps.who.int/classifications/icd10/browse/2010/en#/O24 [/ref]