Real-Time CGM Lowers HbA1c vs SMBG in Type 2 Diabetes

Key Takeaways

• Lower HbA1c was observed with CGM than with SMBG at both prespecified assessments.
• The open-label multicentre randomized trial enrolled adults with type 2 diabetes receiving basal insulin plus SGLT2 inhibitors, GLP-1 receptor agonists, or dual GIP/GLP-1 receptor agonists.
• Similar non-device-related adverse-event incidence was reported, and two severe hypoglycaemia events occurred in the control group.

The FreeDM2 randomized trial found lower HbA1c with real-time continuous glucose monitoring than with continued self-monitoring of blood glucose in adults with type 2 diabetes using basal insulin alongside modern glucose-lowering therapy, with an adjusted week 16 difference of -0.6 percentage points. The comparison enrolled adults already treated with basal insulin plus SGLT2 inhibitors, GLP-1 receptor agonists, or dual GIP/GLP-1 receptor agonists. This open-label multicentre study compared CGM with ongoing SMBG in a tightly defined population. The HbA1c advantage was also present at the second prespecified assessment.

FreeDM2 was an open-label, parallel-design, randomized controlled superiority trial across 24 UK primary and secondary care centres. Adults with type 2 diabetes were eligible if HbA1c was 7.5% to 11.0% while receiving basal insulin and contemporary glucose-lowering therapy. Participants were assigned 2:1 to CGM or continued SMBG using permuted block randomization by site, and mean baseline HbA1c was 8.8% in both groups. Of 469 screened individuals, 329 entered the baseline phase and 303 were randomized, including 198 to CGM and 105 to SMBG. The prespecified endpoints were between-group HbA1c differences at 16 and 32 weeks.

The week 16 and week 32 HbA1c results showed HbA1c of 8.0% with CGM versus 8.7% with SMBG at week 16, for an adjusted difference of -0.6 with a 95% CI from -0.8 to -0.3 and p<0.0001. At week 32, HbA1c was 7.8% with CGM and 8.3% with SMBG, for an adjusted difference of -0.5 with a 95% CI from -0.7 to -0.2 and p<0.0001. The trial included two management phases, beginning with self-management and basal insulin self-titration through week 16. Clinician-supported management followed during weeks 17 to 32, when additional therapies could be started in line with national guidance, and HbA1c remained lower with CGM at week 32.

Non-device-related adverse events occurred at a similar incidence in both groups, and two severe hypoglycaemia events occurred in the control arm. Participants and site staff were not masked to allocation, consistent with the trial's unmasked comparison design. The randomized cohort was 67% male, with a mean age of 60.7 years and a mean diabetes duration of 16.7 years. Over 32 weeks, the randomized comparison showed lower HbA1c with CGM in basal-insulin-treated adults receiving modern therapies.