Objective: Time in range (TIR) is a novel measure of glucose control endorsed by an international consensus group. Given the increased use of FreeStyle Libre (FSL) in the UK, we wanted to investigate the effects of TIR over 14 days of FSL (TIR-14) use on glycaemic control, hypoglycaemia unawareness.

Methods: Clinicians from 101 National Health Service hospitals in the United Kingdom submitted FSL user data, collected during routine clinical care. TIR-14 was defined as the percentage of time the patients with type 1 diabetes spent in the individualised target range of blood sugar which ranged from 3.9 to 10 mmol/L(70-180mg/dl) over 14 days of FSL use. TIR-14 was divided into two categories <= 50%, (Group 1) and TIR-14>50% (Group 2). T-tests were used to compare the baseline and follow-up HbA1c, and GOLD score in the two groups.

Results: Data were available for 10,370 FSL users; age 38 (±18.7) years, 54% female, diabetes duration 16 (±49) years, and BMI of 25.2 (±16.5) kg/m2. TIR-14 data was available for 2191 patients who had at least one follow-up (1422 in Group 1 and 769 in Group 2). There were large variations in the individualised target TIR-14; however, more than 99% of patients had ranges in-between 3.9-10 mmol/mol with a median TIR-14 of 43%(27%-56%). The mean follow-up period was 7.6(±23) months. In Group 1 HbA1c dropped from 8.6% to 7.6% (P<0.0001) while in Group 2 the HbA1c dropped from 7.6% to 7%. (P<0.0001). In an analysis restricted to those with baseline HbA1c of >8.5%, HbA1c dropped from 9.8% to 8.8% (P<0.0001) in Group 1 while in Group 2 it fell from 9.6% to 7.7% (P<0.0001). In the Group I the GOLD score fell by 0.25 (P=0.0005) units while in Group II the GOLD score fell by 0.45 units (P<0.0001).

Conclusion: This population-based study of FSL users demonstrates that TIR-14 of more than 50% is associated with a significantly improved glycaemic control in especially in those with higher baseline HbA1c and is associated with a larger improvement in hypoglycaemia unawareness.


H. Deshmukh: None. E.G. Wilmot: Advisory Panel; Self; Abbott, Dexcom, Inc., Eli Lilly and Company, Insulet Corporation, Medtronic. Speaker’s Bureau; Self; Abbott, Eli Lilly and Company, Insulet Corporation, Novo Nordisk Inc., Sanofi. R. Herring: None. J. Patmore: None. T. Sathyapalan: Research Support; Self; Amgen, Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company, Novo Nordisk A/S. Other Relationship; Self; Ipsen Biopharmaceuticals. R.E. Ryder: Consultant; Self; GI Dynamics Inc. Other Relationship; Self; Novo Nordisk A/S. C. Walton: Speaker’s Bureau; Spouse/Partner; Celgene, LEO Pharma, Novartis Pharmaceuticals Corporation.

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