What is Type 1 Diabetes?
In Type 1 Diabetes the cells in the pancreas that make insulin are completely destroyed by the body’s immune system. This insulin hormone which comes from the beta cells in the islets of the pancreas, controls blood sugar. The role of insulin is to get this sugar into the cells. If the insulin is not produced, the blood sugar will rise markedly—a condition called Type 1 Diabetes.
Type 1 Diabetes and pregnancy
Pregnancy has a profound effect on diabetes and blood sugar control and having diabetes can have a major impact on the baby. Thus we need to look at the issues for the mother, the baby and glucose control/medications.
Issues for the mother
Pregnancy has an impact not only on glucose control but also blood pressure, blood volume hemodynamics and the complications of diabetes. There are four major diabetes complications that have to be considered:
The risk that the eyes may show some progression ranges from 10 to 50% with this risk being proportional to the status of the eyes at the start of the pregnancy. If there is minimal or no damage present then there is about a 10% chance of some changes occurring, if there is a lot of damage present then the risk of progression is about 50%. Hence the need for a formal eye exam ideally pre or early in the pregnancy as how one sees tells little about what is going on in the back of the eye where diabetes causes problems.
When kidney damage occurs it is typically in the form of a leakage of protein in the urine and a rise in blood pressure. Like with the eyes the risk of change is proportional to the starting point. If there is no leakage of protein at the start then the risk of protein leaking and a rise in blood pressure is 10 – 20%. If there is protein in the urine at the start of the pregnancy then the risk of this becoming significantly worse is 40 – 60%. This worsening nearly always settles after the baby is born however if the problems at the start are more severe, leakage of protein and a raised creatinine then the progression of the kidney damage may not revert back to the starting level post partum.
Diabetic nerve damage tends to remain unchanged during pregnancy. Diabetic women who become pregnant are more prone to carpal tunnel syndrome (pain down the wrist and into the hand, usually worse in the morning). This may need a splint if severe and typically goes away after delivery. The one nerve damage complication of diabetes that can make pregnancy very challenging is when the nerves to the stomach are damaged a condition called gastroparesis and associated with nausea and vomiting.
Although there is increased blood volume during pregnancy, circulation problems tend to hold stable during pregnancy. Should a heart attack occur the outcome tends to be more ominous if pregnant. If the woman is pre-pregnant and has a long history of diabetes it may be worth having a cardiac stress test to be sure all is well. This may be particularly important if there is some kidney disease, high cholesterol or a family history of heart attacks.
Issues for the baby
Having diabetes during the pregnancy has important implications for the baby. These can be considered to relate to the first 6 – 8 weeks of pregnancy and then the remainder of the pregnancy.
First 6 – 8 weeks
If the glucose is not well controlled during the first 6 – 8 weeks after conception there is an increased chance that a malformation may occur. Although sometimes minor, they may be serious and include heart, kidney or spine defects. Controlling the blood sugar eliminates this increased risk. The best measure of sugar control is the A1c, the lower the better but is should be at least under 7.0% (in laboratories whose upper limit of normal is 6.1%) prior to conception. Of all the risks for the baby this is by far the most serious and the increased risk can be completely eliminated by controlling the glucose before one gets pregnant.
Remainder of pregnancy
When the sugar is high during the pregnancy it can freely cross into the baby and it is as if the baby converts the sugar into fat. These bigger babies are more difficult to deliver for both the mother and infant at time of labor. It is important to remember that there are other causes of big babies and sugar is only one of the reasons a baby may be large.
If the baby is repeatedly exposed to high sugars from the mother, the baby’s own pancreas starts to make extra insulin so after birth the baby may have some low blood sugars, hypoglycemia.
Jaundice and respiratory distress
Although these babies may be born large they act more as if premature and thus are more prone to jaundice and rarely respiratory problems.
What happens to blood sugars/medications
During the first 14 weeks the amount of insulin required if anything decreases and so one needs to be careful of hypoglycemia. This is likely in part related to morning sickness and some of the hormone changes. From 14 weeks onwards, hormones from the placenta begin to rise and these block how insulin works. Thus the amount of insulin needed to control the blood sugar increases so that by the end of pregnancy the mom with Type 1 diabetes will usually be taking about one and a half to two fold her pre-pregnancy insulin dose.
Some women are on drugs to control cholesterol called statins. These are not considered safe in pregnancy and usually should be stopped once trying to get pregnant. Blood pressure drugs belonging to the ACE (angiotensin converting enzyme) inhibitor class or ARB’s (angiotensin receptor blockers) are also not considered safe for the baby and should be stopped. There are other blood pressure drugs that can be safely used if needed. Finally all women planning a pregnancy should be on prenatal vitamins and most experts recommend extra folic acid for the first three months.