In type 2 diabetes, GMI and HbA1c were comparably associated with cardiovascular and kidney outcomes, whereas TIR was associated with cardiovascular outcomes only.
Key Findings
Results
Higher GMI, higher HbA1c, and lower TIR were each significantly associated with higher risk of the composite of any CVD or all-cause death in adjusted models.
Analysis included 1363 GRADE-CGM Substudy participants with ≥10-day blinded CGM; median follow-up 2.3 years with 74 CVD or death events.
Adjusted HR 1.44 (1.21-1.71) per 1% higher GMI.
Adjusted HR 1.37 (1.16-1.61) per 1% higher HbA1c.
Adjusted HR 0.73 (0.61-0.87) per 20% higher TIR.
Models adjusted for age, sex, race/ethnicity, treatment group, diabetes duration, and baseline eGFR.
Results
Higher GMI and HbA1c were associated with faster eGFR decline, but TIR was not significantly associated with eGFR slope.
Mean eGFR slope in the cohort was -2.37 mL/min/1.73m2/year, estimated with linear mixed-effects models.
Higher GMI was associated with an additional eGFR slope of -0.35 (-0.63, -0.07) mL/min/1.73m2/year.
Higher HbA1c was associated with an additional eGFR slope of -0.38 (-0.65, -0.11) mL/min/1.73m2/year.
TIR was not significantly associated with eGFR slope.
Results
After mutual adjustment of each CGM metric with HbA1c, most associations of CGM metrics and HbA1c with outcomes were attenuated.
Mutual adjustment paired each CGM metric (TIR or GMI) with HbA1c in the same model.
The abstract reports that most associations were attenuated, indicating overlapping rather than clearly independent information.
Conclusions
GMI and HbA1c were comparably associated with cardiovascular and kidney outcomes, whereas TIR was associated with cardiovascular outcomes only.
CGM-derived TIR and GMI were compared with HbA1c as the comparator exposure.
Associations for GMI and HbA1c had similar magnitude for both CVD/death and eGFR decline.
TIR was significant for CVD/death but not eGFR slope.
What This Means
This study looked at whether glucose readings from continuous glucose monitors (CGMs) predict heart disease, death, and kidney function decline in people with type 2 diabetes, compared with the standard HbA1c blood test. It used data from 1363 participants in a substudy of a large trial who wore blinded CGMs for at least 10 days. Participants were followed for a median of about 2.3 years, during which 74 had a cardiovascular event or died.
Higher HbA1c, higher glucose management indicator (GMI, an HbA1c-like estimate from CGM data), and less time in range (TIR) were each linked to a higher risk of cardiovascular events or death. Higher GMI and HbA1c were also linked to faster decline in kidney function (eGFR), but TIR was not clearly linked to kidney decline. When CGM measures and HbA1c were analyzed together, most associations weakened, suggesting they carry overlapping information.
This research suggests that CGM-based measures perform similarly to HbA1c in relating to heart and kidney outcomes in type 2 diabetes, rather than clearly outperforming it. The follow-up was fairly short and the number of events small, so the findings should be interpreted cautiously.
Tang M, Nathan D, Wexler D, Putman M, Higgins J, Zheng H, et al.. (2026). Association of continuous glucose monitoring metrics with cardiovascular and kidney outcomes in type 2 diabetes: Data from the GRADE-CGM substudy.. Journal of diabetes and its complications. https://doi.org/10.1016/j.jdiacomp.2026.109439