Closed-loop Insulin delivery by glucose Responsive Computer algorithms In Type 1 diabetes pregnancies (CIRCUIT)


CIRCUIT is actively recruiting patients based out of Calgary (Foothills and Rockyview Hospitals), Toronto (Mount Sinai Hospital and Sunnybrook Health Sciences Centre), Quebec City, Montreal, London, and Winnipeg. Vancouver is also an expected site.

Strict blood sugar control can reduce pregnancy related complications in women with type 1 diabetes. Women with type 1 diabetes work very hard to try to control their blood sugars during pregnancy. The achievement of strict blood sugar control can be extremely demanding and difficult in pregnant women with type 1 diabetes.

The Tandem t:slim X2 closed-loop system is a new technology that uses a continuous glucose monitor (CGM), insulin pump and computer algorithm (Control IQ) to deliver insulin. The system uses the individual’s glucose values obtained from the continuous glucose sensor (CGM) to adjust the amount of insulin that is needed between meals and overnight.

Standard insulin pumps deliver insulin based on pre-programmed insulin delivery settings on the insulin pump and do not account for the person’s glucose levels. Both the Tandem t:slim X2 with Control IQ technology and standard insulin pumps still require that the user enter information into their insulin pump about the amount and timing of carbohydrate eaten at meals.

The purpose of this research study is to see if the Tandem t:slim X2 with use of the Control IQ technology improves blood sugar control, reduces episodes of low blood sugar, decreases burden of diabetes self-care and partner diabetes distress, and results in healthier pregnancies and children for women with type 1 diabetes.

A trial has demonstrated the safety and effectiveness of the t:slim X2 with Control IQ technology in non-pregnant adults and adolescents. However, pregnant women were not included in the trial and the target glucose range during pregnancy is lower and narrower than outside of pregnancy. Therefore, it is important to evaluate the effectiveness of the Tandem t:slim X2 pump with Control IQ technology in women with type 1 diabetes during pregnancy since there is great potential for benefit in terms of improved blood glucose control and reduced diabetes self-care burden.


Currently recruiting participants: Yes

Eligible gender: Transgender, Female

Eligible ages: 18 to 45

Accepts healthy participants: Yes

Inclusion criteria:

1. Pregnant women age 18 to 45, with at least a one-year duration of type 1 diabetes
on intensive insulin therapy
2. A1c during pregnancy less than 10% and greater than or equal to 6.2%, measured at any time during pregnancy prior to enrollment
3. Less than 14 weeks gestation
4. Pregnant with one baby

Exclusion criteria:

1. Women without type 1 diabetes
2. Women who do not have a viable fetus on an ultrasound
3. Current treatment with drugs known to interfere with glucose metabolism such as high dose systemic corticosteroids
4. Women with advanced kidney disease severe autonomic neuropathy or uncontrolled gastroparesis,
5. Women using a total daily insulin dose of less than 8 units or more than 250 units per day


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Method of contact

Additional information

Contact information

Amy Dunlop

Principal investigator:

Lois E. Donovan

Clinical trial: