Efficacy of Intermittently Scanned Continuous Glucose Monitoring in the Prevention of Recurrent Severe Hypoglycemia

Background: People with diabetes experiencing hypoglycemia are at increased risk of recurrence because of attenuated autonomic warning. We assessed the efficacy of intermittently scanned continuous glucose monitoring (isCGM; FreeStyle Libre™, Abbott) compared with usual-care self-monitoring of blood glucose (SMBG) in reducing this risk in type 1 and insulin-treated type 2 diabetes. Methods: Insulin-treated adults with diabetes and an episode of clinically significant biochemical hypoglycemia (blood glucose [BG] <3.0 mM) or symptomatic hypoglycemia and BG <4.0 mM were randomized to 6 months of isCGM (intensive group) or SMBG (control group) against a background of usual care. The primary outcome was hypoglycemia requiring second-party assistance for recovery. Prespecified secondary outcomes included other hypoglycemic episodes (self-reported, and BG <3.0, 3.0-3.9, <4.0 mM) and change in HbA_1c at 24 weeks. Results: Of 59 participants (mean age 53.6 years, 44.1% males, median HbA_1c 61.8 mmol/mol or 7.8%), 30 were allocated to isCGM and 29 to SMBG. The incidence of severe hypoglycemia was not significantly different between the two groups (incident rate ratio [95% confidence interval]: 1.49 [0.46-5.56], P = 0.47). The incidence of other recorded hypoglycemic episodes in the intervention group was double that in the control group (P < 0.001). There was no difference in the change in HbA_1c between the two groups (P = 0.74). There were seven serious adverse events and none was considered related to the intervention. Conclusions: Although isCGM is safe, it does not appear to have a role in preventing recurrent severe hypoglycemia in at-risk individuals with diabetes.