This study will is a parallel two-group randomized controlled trial that will use the MiniMed 670G hybrid closed-loop system's continuous glucose monitor (GCM) insulin pump and computer algorithm to deliver insulin when in "auto mode". This study will be conducted in women with type 1 diabetes after delivery of their neonate to see if "auto-mode" improves blood sugar control, episodes of low blood sugar, burden of diabetes self-care, alters baby's weight and feeding patterns, and partner diabetes distress.

Women work very hard prior during pregnancy to try to control their blood sugars. However, after delivery, women often feel they need a rest from the intense effort they have put into diabetes self-care during pregnancy due to the demands of caring for a newborn, breastfeeding, and sleep deprivation. Attention to blood sugar control after delivery remains important because these new factors a may increase the risk of nighttime low blood sugar and unrecognized low blood sugar. Blood sugar has been shown to influence the sugar levels in breastmilk. How this affects the child has not been well study.

The MiniMed 670G hybrid closed-loop system uses a continuous glucose monitor (GCM) insulin pump and computer algorithm to deliver insulin when in "auto mode". The system uses input about 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.

Manual mode of the insulin pump delivers insulin based on preprogrammed insulin delivery settings on the insulin pump regardless of the person's glucose levels.

This is a randomized controlled pilot trial followed by an observational cohort study in postpartum women with type 1 diabetes, of the MiniMed 670G hybrid closed-loop insulin delivery system with early 6 to 10 days postpartum) versus delayed (12 weeks postpartum) auto mode enabled MiniMed 670G hybrid closed-loop insulin delivery system. This study will assess the impact of auto mode enabled hybrid closed-loop on glycemic control, occurrence of maternal hypoglycemia, and burden of diabetes self-care, infant weight and feeding practices. The investigators will also assess the acceptability of the auto mode enabled MiniMed 670G during lactation and postpartum and the feasibility of conducting a larger multicentre trial.

Inclusion Criteria:

• Women aged 18 to 45, with at least a two year duration of type 1 diabetes, on intensive insulin therapy (at least 3 daily insulin injections or insulin pump) with a Hba1c during pregnancy < 9.9 % at study entry who are confirmed by ultrasound, to have a viable singleton pregnancy between 12 and 32 weeks gestation and are not planning to conceive another pregnancy in the first 24 weeks postpartum.

Exclusion Criteria:

• Non-type 1 diabetes
• Any other physical or psychological disease which, in the opinion of the investigator, is likely to interfere with the normal conduct and interpretation of the study results
• Current treatment with drugs known to interfere with glucose metabolism as judged by the investigator such as high dose systemic corticosteroids, non-selective beta-blockers and MAO inhibitors.
• Known or suspected allergy against insulin.
• Women with advanced nephropathy (eGFR<45), severe autonomic neuropathy, uncontrolled gastroparesis or severe proliferative retinopathy, as judged by the investigator, that is likely to interfere with the normal conduct of the study and interpretation of study results.
• Total daily insulin dose of less than 8 or greater than 250 units/day.
• Severe visual or hearing impairment
• Unable to speak and understand English (or French)
• Planning to conceive another pregnancy within the first six months postpartum