Introduction: The aim of this study was to evaluate change in laboratory-measured HbA1c in patients with either type 1 diabetes (T1D) or type 2 diabetes (T2D) on insulin therapy following initiation of the FreeStyle Libre™ flash glucose monitoring system.
Methods: This was a retrospective observational study on adults with T1D or T2D on insulin, who were started on the FreeStyle Libre system as part of standard care. HbA1c was recorded at initiation and at 3-month intervals thereafter.
Results: The analysis included 131 patients with T1D and 176 patients with T2D on insulin. Mean HbA1c decreased significantly by 3 months following initiation of the FreeStyle Libre system, both in T1D (- 0.75%, p < 0.001) and in T2D (- 0.54%, p < 0.001). Reductions were maintained for 12 months. Change from 3 to 12 months was not significant either in T1D or T2D. Subgroup analysis showed significant reduction in patients with a baseline HbA1c > 7.5-10%, both in T1D (- 0.59%, p < 0.001) and in T2D on insulin (- 0.62%, p < 0.005) at 12 months. Reductions for subjects with HbA1c > 10% were - 4.66% in T1D and - 3.73% in T2D. No change was seen for subjects with a baseline HbA1c ≤ 7.5% (58 mmol/mol). Linear regression confirms that baseline HbA1c is strongly negatively correlated with subsequent change in HbA1c in T1D and in T2D.
Conclusions: Patients with T1D or T2D show a reduction in HbA1c by 3 months following initiation of the FreeStyle Libre system. The mean fall in HbA1c at 3 months is strongly negatively correlated with starting HbA1c. This reduction is maintained over 12 months. The significant benefit is seen in patients with a starting HbA1c > 7.5% (58 mmol/mol).
Keywords: Flash glucose monitoring; FreeStyle libre; Glycemic control; HbA1c; Type 1 diabetes; Type 2 diabetes.