Glucose monitors modestly lower HbA1c in type 2 diabetes

Continuous glucose monitors have spread rapidly from specialist diabetes clinics into everyday use, but most of the evidence behind them comes from settings very different from an ordinary GP surgery. For adults with type 2 diabetes managed in primary care, the key questions are whether wearing a sensor actually improves long-term glycaemic control, and whether it helps or burdens daily life. HbA1c is the standard marker of glucose control over time, so shifting it meaningfully matters for diabetes management. This review set out to pool the randomised evidence on CGM specifically within primary care.

Following PRISMA 2020 guidelines, the authors searched four databases for randomised controlled trials published through 9 July 2025 that reported HbA1c, quality of life, diabetes distress or device satisfaction. From 739 records, 4 multisite RCTs (reported across 6 papers) met the inclusion criteria, representing 566 adults with type 2 diabetes managed in primary care. Two trials used real-time CGM, while the others used retrospective or intermittently scanned CGM. Participants attended primary care visits during the trials, receiving diabetes management and medication changes as required, and HbA1c outcomes were pooled at 6-8 months and 12-14 months using random-effects models.

CGM significantly improved glycaemic control, with a pooled HbA1c reduction of 0.46% at 6 to 8 months and 0.33% at 12 to 14 months compared with control. Device satisfaction also improved among CGM users. Quality of life, however, showed no differences between groups — wearing the sensor neither improved nor worsened how participants rated their lives. The benefit at the later time point was smaller than at the earlier one, suggesting some attenuation of the effect over a year.

This analysis extends the case for CGM beyond insulin-intensive specialist care into the primary care settings where much type 2 diabetes is managed, and the authors argue it offers advantages in patient engagement, particularly within a multidisciplinary team approach. The evidence base remains thin: just 4 trials and 566 participants, with a mix of CGM technologies. The authors flag important open questions, including whether benefits extend to non-insulin-using patients currently ineligible for CGM coverage, to underserved groups, and whether newer, more accurate sensors change the picture.

For anyone with type 2 diabetes — or anyone curious about glucose sensors more broadly — this is a reason to think CGM can produce a modest, real improvement in long-term glucose control within routine GP-level care, not just specialist clinics. It is equally a reason to keep expectations calibrated: the HbA1c reduction shrank somewhat by 12-14 months, and quality of life did not improve, so the device is a tool rather than a transformation. Whether the findings apply to people not using insulin remains an open question the trials did not settle.