Objective: Limited information is available on chronic use of sodium glucose cotransporter 2 inhibitors in type 1 diabetes (T1D). We conducted a retrospective review of T1D patients on Dexcom G4Platinum continuous glucose monitors (DCGMs) >1 year (mean, 4.6 years) who were prescribed canagliflozin (CANA) 100 mg daily and had a baseline DCGM 30-day download prior to and a second download after at least 1 month (mean, 3.7 months) taking CANA 100 mg daily. The glycemic, weight, and systolic blood pressure (SBP) effects are reported. Methods: We identified 27 patients meeting the selection criteria: 14 men; 25 white; 22 on pump; average T1D duration, 34 years (range, 12 to 48 years); average hemoglobin A1C (A1C), 7.6% (range, 6.1 to 9.8%); 22 with baseline A1C 7.0% or higher. All patients had an estimated glomerular filtration rate (eGFR) at baseline of 60 mL/min/1.73 m(2) or higher and were normotensive or on stable therapy. On average, 29 days of CGM data was reviewed. Total daily insulin dose (TDD) was available in 21 patients. We identified 27 patients who were judged to be candidates for CANA but did not have any change in glycemic therapy other than insulin adjustment as controls. Results: CANA resulted in significant reductions in mean blood glucose, CGM standard deviation, time in hyperglycemia, A1C, weight, SBP, and TDD, with increased time in target, with minimal increase in hypoglycemia and no significant change in eGFR. Three females developed genital mycotic infections but continued therapy, 2 developed ketoacidosis from insulin interruption. Conclusion: CANA offers promise as adjunct therapy in T1D, though caution is advised.