Diabetes in pregnancy can be diabetes that was present before conception (type 1 or type 2) or it can be first diagnosed in pregnancy which is known as Gestational Diabetes. Pregnant women with diabetes should be seen weekly and the blood sugars closely watched to assess if adding or changing medication is necessary. As the baby grows and the pregnancy progresses, the hormones from pregnancy stop insulin (either from the pancreas or given by injection) from working so well (insulin resistance) which means that any medications to treat the diabetes may need to be increased.

High sugars in pregnancy are associated with poor outcomes for the mother and the baby:

  • Premature delivery
  • Stillbirth - 2-4x increased risk of stillbirth
  • Neonatal Death - increased risk of hypoglycemia, hyperbilirubinemia, hypocalcemia, respiratory distress syndrome.
  • Macrosomia - this is when the baby is born at a very large weight (>4500g/9.9lbs). It happens if high levels of sugar in the motherís blood are delivered to the baby. The baby doesnít have diabetes so with all the extra sugar, the babyís pancreas makes more insulin and the bay gets fat. If the baby is too big, the mother cannot push it out causing risk of (serious) injury to the mother and the baby, increasing the risk of caesarean section.

  • Malformations Ė 8 x increased risk of heart defects compared to non-diabetic pregnancy.
  • Preeclampsia - high blood pressure in pregnancy which can be associated with liver and kidney failure and seizures in extreme cases.
  • Polyhydramnios - increased volume of amniotic fluid around the baby Ė increases risk of premature birth.


Ideally, women who are known to have diabetes should plan their pregnancies and aim to have as good control of their sugar levels as possible prior to conceiving. The babyís organs develop in the first 3 months of pregnancy and so it matters how good your sugars are from the very beginning. If you are planning to become pregnant, discuss with your doctor or diabetes educator to have assistance in achieving good control before becoming pregnant.

If you do have an unplanned pregnancy, see your doctor as soon as possible, so that there is no delay to achieving good control.

As pregnancy progresses, the hormones from the placenta mean that the doses of medications are probably going to need to increase. This is true for all types of diabetes (Type 1, Type 2 and Gestational).

Type 2 diabetes in Pregnancy

Insulin, Glyburide (Glibenclamide) and Metformin (Glucophage) are safe in pregnancy and do not need to be discontinued. It is important to remember that not all medications are safe for use in pregnancy. Some medications will need to be changed/stopped when you become pregnant Ė another good reason to plan. Many women with type 2 diabetes also have high blood pressure and high cholesterol. Most cholesterol-lowering medications are not licensed for use in pregnancy and many diabetes and blood pressure medications need to be changed also.

Type 1 diabetes in Pregnancy

These women are only on insulin, so the drug does not need to be changed but the doses will. The first trimester of pregnancy is associated with reduced appetite, nausea and vomiting and this predisposes to low blood sugar (hypoglycaemia) and diabetic ketoacidosis. Throughout pregnancy, close blood glucose monitoring helps to make adjustments to therapy. Many type 1 women who are on insulin injections choose to change to insulin via pump as this has been shown to achieve better glucose control in pregnancy. There is also the possibility to use continuous glucose monitoring as another tool to improve control.


When you are pregnant, you have much higher hormone levels in your blood which cause insulin resistance (your insulin doesnít work as well) so your pancreas makes more insulin. Other things that make you more likely to get insulin resistance in pregnancy are increased fat deposits, decreased exercise, and increased appetite. These changes ensure that the developing baby has enough fuel and nutrients at all times. Gestational diabetes occurs when the pancreas canít make enough insulin to overcome the insulin resistance during pregnancy. This may predispose some women to develop diabetes during pregnancy.

You may be at higher risk of developing Diabetes in Pregnancy if you:

  • Have a family history of type 2 diabetes, especially in first degree relative (mother, father, brother, sister)
  • Have had gestational diabetes in a previous pregnancy
  • Are obese before pregnancy (BMI > 30kg/m2)
  • Have had a previous baby weighing 9 lbs at birth
  • Have a personal history of abnormal glucose tolerance
  • Are African-American, Hispanic-American, Native American, South or East Asian, Pacific Islander
  • Were heavier than 9 lbs when you were born
  • Have polycystic Ovarian Syndrome
  • Have essential Hypertension or pregnancy-related hypertension
  • Have previously had an unexplained malformed or stillborn baby.


All women not previously known to have diabetes get screened for Gestational Diabetes between 24 and 28 weeks of pregnancy because this is the time when the pregnancy hormones that can cause diabetes peak.

  • 50 gram oral glucose challenge test >140mg/dL.
  • If the initial test is elevated a confirmatory test is performed which is a 100 gram oral glucose tolerance test which spans 3 hrs. The targets are:

    Fasting < 95mg/dL
    1 hour < 180mg/dL
    2 hour < 155mg/dL
    3 hour < 140mg/dL
    Diabetes is diagnosed if any 2 of these 4 values are elevated


The goal is to maintain normal glucose levels to ensure a good outcome for both mother and baby. The woman with gestational diabetes is required to monitor blood glucose levels throughout the day via fingerstick. The aim is to maintain fasting (before eating in the morning) blood sugars between 60 and 95 mg/dL and 2 hr postprandial (after meals) blood sugars < 120 mg/dL.

Upon diagnosis, patients with gestational diabetes should receive nutritional counseling from a registered dietician and be placed on an appropriate diet. They are advised to take regular exercise as this can also help to lower blood glucose levels.

The goals of nutritional therapy are to:

  • Achieve normal blood glucose levels
  • Prevent ketosis
  • Provide adequate weight gain
  • Contribute to fetal well-being
  • Medicines for Gestational Diabetes

    If diet and exercise arenít working, medications to help lower the blood sugar should be started. The two options for medical therapy in pregnancy are insulin or tablets : glyburide or metformin, which may be a reasonable alternative for women that fail diet therapy or refuse to take, or are unable to comply with insulin. As with insulin therapy, glyburide must be carefully balanced with snacks to prevent low blood sugar in the mother, which is also not good for the baby.

    Women with gestational diabetes are placed on insulin therapy when blood sugar levels remain too high despite diet, exercise and sometimes tablets. An insulin regimen is calculated and adjusted as necessary to maintain normal blood sugar levels. Frequent self-monitoring helps your healthcare providers to make these adjustments. At least four glucose measurements are required daily and are needed to optimize therapy and ensure a smooth increase as requirements increase with pregnancy progression.


    During pregnancy, pre-existing complications of diabetes can get worse, particularly eye and kidney problems.


    Diabetic Retinopathy can deteriorate in pregnancy. Make sure you are up to date with your annual eye checks before pregnancy. Women who already had diabetes before they became pregnant should have their eyes checked each trimester Ė first 3 months, middle 3 months and last 3 months to ensure that they do not develop any problems.


    You should have blood and urine tests in each trimester as well to pick up any deterioration in function.

    Blood Pressure

    Some women develop high blood pressure in pregnancy. This can become complicated by other problems with the liver, kidneys and can deteriorate into headaches or seizures. This condition is known as Pre-eclampsia. Throughout your pregnancy, your blood pressure should be monitored. If you develop swelling of your ankles, this may be normal, but blood pressure and kidney function should be tested to make sure.

    Growth of the Baby

    Although there are no rules, in general the patient with diabetes in pregnancy will receive at least one ultrasound in the third trimester to monitor the fetal growth. This is helpful to predict if the woman might benefit from scheduled cesarean section if the baby looks like it is >4500 g or to see who may benefit from induction of labor before the fetus grows too large.

    It is also common practice to initiate fetal testing in the third trimester to ensure fetal wellbeing. The test that is utilized varies by institution and practice and may be either weekly nonstress tests or biophysical profiles. The timing for initiation of testing also varies but generally begins at approximately 32 weeks gestation.


    It is sometimes recommended that women with diabetes should not go past 40 weeks gestation because of the increased risk of stillbirth. Depending on the perceived risk, induction of labour may occur at 38-39 weeks gestation. Women who have pre-existing complications of diabetes or large for gestational age babies may be recommended to have a caesarean section.

    It is important that the motherís blood sugar is kept normal during labour to reduce the risk of problems for the baby. The baby will make more insulin to normalize their blood sugar and when they are separated from the motherís blood supply when the cord is cut, they will have too much insulin and their blood sugar can fall very low.

    Insulin requirements usually decrease during labor, as uterine contractions require energy and women in labour donít usually eat much. Women with gestational diabetes had normal blood sugar levels without use of insulin or diabetic tablets during pregnancy rarely require insulin during labor and delivery. Women with gestational diabetes who used insulin or glyburide to keep their sugars normal may need an insulin infusion (given via a vein) during labor and delivery. We generally check blood glucose levels every 1-2 hours during active labor in these women and will begin an insulin infusion if needed. It is generally best to withhold long-acting insulin in favor of using an insulin infusion as needed, in women in labor.


    Following delivery of the baby and the placenta, the womanís hormone levels return to pre-pregnancy levels and she will need lower doses of medications. The doses of insulin, glyburide etc, will need to be reduced. Often women who did not require medication pre-pregnancy return to this and can completely stop their insulin or tablets after the birth of the baby. This should of course be discussed with your doctor.

    Women with gestational diabetes are usually able to resume a regular diet after the birth. They should discuss with their doctor whether they should completely discontinue blood glucose or should continue for up to 48hrs after delivery.

    All patients with gestational diabetes should repeat the 75 gram oral glucose tolerance test six weeks after the birth of the baby to confirm that they have returned to normal and do not actually have type 2 diabetes.


    - Postpartum depression is increased amongst women with gestational diabetes
    - Gestational Diabetes in future pregnancies is at an increased risk
    - Type II Diabetes risk is increased

    Written by Dr Carla Ming Reese, Obstetrician/Gynaecologist