Cadisegliatin as Adjunctive Therapy to Insulin in Participants With Type 1 Diabetes Who Are Using Hybrid Closed Loop (HCL) Systems

Key Inclusion Criteria:

* Participants \>= 18 years of age
* Fasting C-peptide levels \<0.6 ng/ml
* Average TIR \< 70% recorded on their personal CGM data collected over the past 7 days prior to Visit 1
* Currently on a hybrid closed loop device for at least 3 months and willing to stay on the same model of pump device for study duration
* Willing to wear a study provided CGM for study duration
* Total bilirubin ≤2×ULN, ALT and AST ≤3×ULN

Key Exclusion Criteria:

* Have Type 2 Diabetes Mellitus (DM), monogenic diabetes, maturity-onset diabetes, other unusual or rare forms of DM, or diabetes resulting from a secondary disease.
* Have been hospitalized for DKA within 3 months
* Have uncontrolled hypothyroidism or hyperthyroidism
* Have QTcF interval \> 450 msec for males or \> 470 msec for females
* Have a personal or family history of long QT syndrome, Torsades de pointes, or other complex ventricular arrhythmias
* Have persistent, uncontrolled hypertension
* Have clinically significant cardiovascular or cerebrovascular disease
* Have proliferative retinopathy or maculopathy requiring acute treatment
* Have a serious concomitant systemic disorder including but not limited to HIV or active Hep B or Hep C
* Have been diagnosed and/or treated for malignancy within 3 years
* Have used any of the following medications within the specified time periods: any non-insulin anti-diabetic therapies (e.g.SGLT-2 inhibitors, GLP-1 receptor agonists, metformin, sulfonylureas, DPP-4 inhibitors, pramlintide, a-glucosidase inhibitors, or glucose dependent insulinotropic polypeptide agonists) within 30 days, antipsychotic medications (e.g. olanzapine, risperidone, clozapine, quetiapine, and haloperidol) within 30 days, systemic corticosteroids for ≥7 days for a temporary medical condition within 30 days,