Continuous Glucose Monitoring in Women With Type 1 Diabetes in Pregnancy

Before conception it is very important to get blood sugars very well controlled. This is
because high blood sugars at the time of conception and in the very early weeks of pregnancy
can be associated with a higher than average risk of malformations in the baby. If however,
blood sugars are very close to normal, then the chance of a person with type 1 diabetes
having a baby with malformations is the same as that in the general population.

During pregnancy it is very important to get blood sugars very well controlled. This is
because high blood sugar levels can cause a baby to grow bigger than the average baby. This
can make delivery of the baby difficult, leading to potential injury for the baby as well as
for the mother. In addition, the baby may have problems after birth which include breathing
difficulties and low blood sugar which may require the baby to be admitted to the intensive
care unit. When pregnant, diabetics can have difficulty controlling blood sugar.

The standard treatment of women with type 1 diabetes before pregnancy and in pregnancy is
the use of insulin and diet and monitoring of blood glucose values by home blood glucose
meters before and after each meal.

This trial is trying to evaluate the benefit of using a real-time continuous glucose monitor
(CGM) during pregnancy to help get blood sugars into target. The CGM system that will be
used in the study at Sansum is the Dexcom SEVEN PLUS CGM, which has been approved in the
United States. The Dexcom SEVEN Plus is made by Dexcom and has its own handheld receiver
for displaying and storing data from the sensor.

These CGM devices use a glucose sensor that is inserted under the skin. The glucose sensor
can be placed under the skin anywhere on the body but usually on the abdomen, flank or arms.
The sensor measures the glucose in the interstitial fluid under the skin every 5 minutes
and sends the values to a receiver. The wearer can see the glucose values on the receiver.
The wearer still needs to check blood sugar with a home glucose meter. The Dexcom sensor
will work for 6 days and then needs to be replaced. This is done by the wearer, at home.
We believe that using this CGM sensor may help improve blood sugar control in women planning
pregnancy and in pregnant women compared to standard monitoring; however, it is not yet
clear whether or not it will.

Inclusion Criteria:

- DM1 more than one year

- Age 18-40 years

- Uses an insulin pump or more than 3 shots per day

- Planning pregnancy or pregnant

- Wishes to optimize glycemic control before or during conception

- If pregnant: Live singleton fetus gestational age less than 12 weeks and 6days at
enrollment

- Subject doesn't plan to move

- Informed Consent

Exclusion Criteria:

- Type 2 diabetes

- Gestational diabetes onset

- Estimated GFR <60 ml/min/1.73

- Previous participation in the study

- Regular home user of Continuous Glucose Monitor in the previous 3 months

- Inpatient psychiatric treatment in the past 6 months

- Premixed fixed dose of insulin use at the time of enrollment

- Medical disorder/medication that would affect the Continuous Glucose Monitor or
protocol

- Pre-pregnant with HbA1c less than 7.0% or more than 10.0%

- Pregnant with HbA1c less than 6.5% or more than 10.0%

- Higher order pregnancy

- Known potentially major fetal anomaly (EUROCAT criteria)