962-P: Assessment of Hybrid Closed-Loop Impact upon Glycemic Control, Weight, and Retinopathy

Background: We sought to assess real-world outcomes in adults with type 1 diabetes commenced on hybrid closed loop (HCL). Methods: Observational study of 254 adults following conversion from CSII to HCL in a secondary care setting. Outcomes included change in CGM metrics, HbA1c, weight and eye disease. Results: Mean age was 41±14 years (70% female) and diabetes duration was 22±12 years. 102 were on Tandem CIQ, 79 on Medtronic 780G, 57 on Omnipod 5 and 16 on CAM APS. HbA1c fell by 0.64% (p 0.001, mean follow up 467 days). Where HbA1c 7.5% at baseline, the fall in HbA1c was 0.91% (p 0.001). HbA1c 7.5% increased from 39% to 65% and HbA1c 9% decreased from 12% to 5% (p 0.001). CGM metrics are presented below. There was no significant change in weight (+0.1 kg, p = 0.610) over a mean follow up of 356 days. Those with a 5% improvement in TIR experienced greater weight gain (+0.6kg vs -1.2kg, p = 0.012). Of 113 individuals with routine retinal screening data, only 17 experienced any degree of worsening and this was not associated with change in TIR or HbA1c (but was associated with low baseline TIR p = 0.03). In a logistic regression model, lower age and higher HbA1c were associated with superior TIR response to HCL (but gender, BMI and socioeconomic deprivation were not). Conclusion: HCL is associated with substantial glycemic benefits - particularly in those with highest baseline HbA1c. The extent of weight gain and EWDR appears to be small. Disclosure F.W. Gibb: Speaker's Bureau; Abbott. Advisory Panel; Insulet Corporation. Speaker's Bureau; Novo Nordisk. S. Forbes: None. A.R. Dover: None. R.H. Stimson: None. M. Lyall: None.