Background: Few long-term RCTs compare Hybrid Closed Loop (HCL) insulin delivery to manual (non-HCL) insulin dosing in type 1 diabetes (T1D).

Objective: To examine glycemic and psychosocial outcomes in adults with T1D using HCL vs. manual insulin dosing with self-monitoring of blood glucose (SMBG) for 6 months.

Methods: Adults using multiple daily injections or pumps with SMBG were randomized 1:1 after insulin dose optimization to 26 weeks of HCL (Medtronic 670G) or continuation of current therapy. The primary outcome was time in target range (70-180mg/dL) with masked CGM during the final 3 weeks. Secondary outcomes included other CGM metrics, HbA1c, treatment satisfaction (DTSQs) and diabetes distress (PAID). Intention to treat analysis was performed with ANCOVA or rank sum test.

Results: HCL and control groups were well balanced at baseline (Table). At 26 weeks, mean (95% CI) CGM time in range with HCL was greater by 14.8% (11.1, 18.5), with reduced high and low glucose time, and lower HbA1c. There were no between-group differences in treatment satisfaction or diabetes distress (Table).

Conclusions: HCL provided a significant and sustained glycemic benefit compared with standard therapy. Results will inform potential users and health professionals and a cost-benefit analysis may facilitate HCL access.


S.A. McAuley: Advisory Panel; Self; Medtronic. Research Support; Self; Medtronic, Roche Diabetes Care. Speaker’s Bureau; Self; Lilly Diabetes, Roche Diabetes Care. M.H. Lee: Research Support; Self; Medtronic. Speaker’s Bureau; Self; AstraZeneca, Medtronic. B. Paldus: Research Support; Self; JDRF. Speaker’s Bureau; Self; Australian Diabetes Society, Medtronic. S. Vogrin: None. M.B. Abraham: Speaker’s Bureau; Self; Lilly Diabetes. L. Bach: None. M. Burt: None. N. Cohen: Advisory Panel; Self; Abbott, AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Lilly Diabetes. Research Support; Self; Ypsomed AG. Speaker’s Bureau; Self; Novo Nordisk A/S. P.G. Colman: None. E.A. Davis: None. C. Hendrieckx: None. M. de Bock: None. J. Holmes-Walker: None. J. Kaye: Advisory Panel; Self; Abbott. Speaker’s Bureau; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company, Novo Nordisk Inc. K. Kumareswaran: None. R. MacIsaac: None. R.W. McCallum: None. C.M. Sims: Stock/Shareholder; Self; Medtronic. J. Speight: Research Support; Self; Abbott, AstraZeneca, Medtronic, Sanofi-Aventis. Speaker’s Bureau; Self; American Diabetes Association, Australian Diabetes Society, Roche Diabetes Care. S. Stranks: Advisory Panel; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Lilly Diabetes, Sanofi-Aventis. S. Trawley: None. V. Sundararajan: None. G. Ward: None. A.C. Keech: Advisory Panel; Self; Amgen, Kowa Research Institute, Inc. Consultant; Self; Sanofi-Aventis. Speaker’s Bureau; Self; Abbott, Amgen. A. Jenkins: Advisory Panel; Self; Abbott, Medtronic. Research Support; Self; Abbott, GlySens Incorporated, Medtronic, Sanofi-Aventis. T. Jones: Other Relationship; Self; Medtronic. D.N. ONeal: None.

Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. More information is available at