Popular glucose monitors did not reliably reflect real blood sugar control in people without diabetes
Published Oct 1, 2025
Methods
Researchers compared continuous glucose monitor (CGM) readings with standard HbA1c blood tests across 972 adults aged 40 and older, some with diabetes, some with prediabetes, and some with normal blood sugar, to see how well the two measures agreed with each other in each group.
Findings
CGM metrics closely tracked HbA1c in people with type 2 diabetes. That relationship weakened substantially in people with prediabetes, and essentially disappeared in people without diabetes — in that group, CGM readings were largely unrelated to their HbA1c result.
Caveats & Context
This is a single snapshot comparison (cross-sectional), not a study of health outcomes, so it does not show whether wearing a CGM changes anything for people without diabetes — only that the numbers it produces do not line up with the standard clinical blood sugar test in that group. It also cannot say whether CGM data might still be useful as short-term feedback on how specific meals or activities affect an individual, just that it should not substitute for an HbA1c test.
Lack of Association Between Hemoglobin A1c and Continuous Glucose Monitor Metrics among Individuals with Prediabetes and Normoglycemia
Diabetes Technology and Therapeutics · doi.org/10.1177/15209156251379506