Sherree saw me for management of her first pregnancy. She had been a diabetic for five years before her pregnancy.
Before her first visit with me, she had an appointment with her endocrinologist. Prior to being pregnant, he had managed her diabetes with oral medications – Metformin and Diamicron. Now that she was pregnant he switched her to insulin. As well her blood pressure was elevated when she saw him and so he commenced her on Aldomet.
Sherree’s first visit with me was when she was eight weeks pregnant. She was already needing considerable insulin (124 units) each day to keep her blood sugar level in the normal range. She was requiring 250mg of Aldomet twice per day to maintain a normal blood pressure.
Her pregnancy overall progressed well. Her insulin and requirements gradually increased, as expected. At 35 weeks pregnant she was on 186 units of insulin per day. She also had biochemical evidence of preeclampsia on a background of hypertension. She now required an Aldomet dose of 1000 mg four times per day to maintain her blood pressure in the normal range.
I had advised her, as I do all pregnant patients with diabetes managed by insulin, that they can expect increasing insulin requirements as the pregnancy advances. That is because the hormones released by the placenta in pregnancy that cause the mother’s blood sugar level to increase and also and makes her body less sensitive to insulin-less able to use it properly. Hence more insulin is required to keep the blood sugar level in the normal range.
Sherree contacted me on a Sunday evening by Facebook private messaging when she was 36 weeks gestation to say that she had falling insulin requirements. She stated in her message: “I have noticed that my BSL has been low and I haven’t had my insulin at least once a day and I have been having hypo’s more often.”
I read this message about 10 pm that Sunday evening. Alarm bells went off. The falling insulin requirements implied there could be placental insufficiency, which would put the baby’s life at risk. My other concern was that her baby would not tolerate her blood sugars being too low. That implied her unborn baby would also have low blood sugar levels and as a consequence was at risk of dying in the uterus.
I phoned Sherree and asked her to attend the hospital immediately for further assessment.
At the hospital, there was monitoring of the baby and further diabetes and preeclampsia assessment done. Her insulin requirements continued to be dramatically less than it had been, but her preeclampsia was stable. I advised Sherree that is was too dangerous for her baby to continue the pregnancy and that we should deliver her baby soon.
The steroid Celestone Chronodose was given to Sherree to help mature her baby’s lungs. At 36 weeks pregnant there is an increased risk of the baby having hyaline membrane disease (immature lungs) that is the case later in the pregnancy and so needing ventilation support after birth. This risk was greater because of the diabetes.
I assessed Sherree vaginally for the possibility of a vaginal delivery. The cervix was not suitable for induction. I suggested a Caesarean section delivery. That was done under a spinal anaesthetic and was uncomplicated. Her son was born in good condition with a birth weight of 3150 grams.
Postnatally mother and son have done well. Sherree’s insulin needs to be reduced immediately after birth as is usual. Also, I was able to reduce her Aldomet to 500mg for times per day.
When I saw her for her six weeks postnatal visit she and baby were both doing well. Her endocrinologist had continued to reduce her insulin dose and she was now on 30 units per day. Her Aldomet dose was 250mg twice per day. Her blood pressure was in the normal range and so I suggested she cease the Aldomet and see her GP for further blood pressure check after doing so to make sure the blood pressure remained in the normal range.
Diabetes in pregnancy
Diabetes is a common but potentially very serious complication of pregnancy. About 5 – 8% of pregnant women will develop diabetes in pregnancy. Most diabetes in pregnancy is pregnancy induced (called ‘gestational diabetes’) but some pregnant women are diabetics for years prior to conceiving.
Elevation of the blood sugar level in pregnancy is caused by hormones released by the placenta during pregnancy. The placenta produces a hormone called the human placental lactogenic (HPL). This hormone is similar to growth hormone in action and so helps the baby grow’. It modifies the mother’s metabolism and how she processes carbohydrates and lipids. HPL raises a pregnant woman’s blood sugar level and makes her body less sensitive to insulin, and so she is less able to use insulin properly. If the body doesn’t use insulin as it should, the blood sugar level goes up. The HPL hormone elevates the blood sugar level so that the baby gets enough nutrients from the extra sugar in the blood.
At 15 weeks of pregnancy, another hormone, human placental growth hormone, increases production. This also affects the mother’s blood sugar level. This hormone helps regulate the mother’s blood sugar level, again to make sure that the baby gets enough nutrients. It can, however, cause the mother’s blood sugar level in the mother to go too high.
The impact of these changes gradually increases during the pregnancy. Hence we do the diabetes screening at about 28 weeks when it is likely if there is going to be gestational diabetes it will be manifest. In high-risk cases, there is screening in early pregnancy. A normal oral glucose tolerance test result at 28 weeks’ pregnancy does not mean that gestational diabetes will not develop later in pregnancy. I have had quite a number of scenarios such as this has happened and diabetes has been diagnosed in the third trimester of pregnancy. Hence I check a patient’s urine each visit for sugar. If there are clinical concerns such as a very large baby or hydramnios (extra amniotic fluid around the baby) then diabetes checking will be repeated.
Diabetes can affect the unborn baby in a number of ways…
- Poorly managed diabetes can result in difficulty conceiving.
- Developmental abnormalities. Poorly controlled diabetes at the time of conception and in early pregnancy can result in abnormalities in any developing organ system, but cardiovascular and neural tube defects are among the most frequent.
- Excess growth (macrosomia). Gestational diabetes may cause your baby to be very big and have extra fat. If your blood sugar is too high, then your baby will have a high blood sugar level that is too high also. The baby’s pancreas will make more insulin to deal with this. Insulin acts like growth hormone in the fetus and so this can result in excessive growth. Macrosomia is likely to cause delivery challenges and increased vaginal delivery risks because the baby is too big for the birth canal. If the baby is very large it is often better to do an elective Caesarean section instead.
- Diabetes is associated with preeclampsia and with placental insufficiency without preeclampsia. Placental insufficiency can reduce baby’s growth and has an increased risk of fetal distress and death. Placental insufficiency is suggested if there are falling insulin requirements.
- Sudden death of the unborn baby in the uterus. This is thought due to the baby’s blood sugar being too low. Just as you can have a ‘hypo’ the baby can also have a ‘hypo’. Baby cannot tolerate this especially if prolonged.
- Preterm delivery is sometimes needed because of diabetes, which can result in extra risk for the newborn baby.
- Difficulty breathing (respiratory distress syndrome/hyaline membrane disease). Sometimes, babies have trouble breathing on their own right after they are born. This breathing difficulty is more likely in babies whose mother has diabetes. This should go resolve once the lungs become stronger, but the baby will need ventilation support and sometimes other measures to help increase lung maturity.
- Difficulty maintaining a normal blood sugar level immediately after birth. This is because the baby may have been making more insulin in the uterus than is needed after birth. So baby’s sugars need close monitoring until it is apparent this is not a problem. It is for this reason that the babies of women with insulin-dependent diabetes are admitted to the special care nursery after birth. It is usually only for a short lime, long enough to be sure baby’s sugars are ok and baby’s breathing is ok. Hypoglycemia (low blood sugar) in babies is easily treated by giving the baby a glucose solution to quickly raise the blood glucose level. Feeding the baby should also raise the blood glucose level.
These considerations are much more likely in insulin-dependent diabetics, especially those who are more severe.
During my years working in Oxford, England I had extra training in the management of diabetes in pregnancy. I have managed hundreds of pregnant women with diabetes of all different grades of severity over many years. The keys to a good outcome are good patient compliance, the patient conscientiously trying to maintain optimal blood sugar levels during pregnancy, being diligent in patient’s pregnancy management and good communication with the patient and the support of a good endocrinologist.