Continuous Glucose Monitoring Metrics in the Assessment of Glycemia in Moderate-to-Advanced CKD in Diabetes

Introduction: Glycated hemoglobin A1c (HbA1c) has reduced reliability in advanced chronic kidney disease (CKD) owing to factors influencing red cell turnover. Recent guidelines support the use of continuous glucose monitoring (CGM) in glycemic assessment in these patients. We evaluated relationships between HbA1c and CGM metrics of average glycemia and glucose variability (GV) in moderate-to-advanced CKD. Methods: There were a total of 90 patients with diabetes in CKD stages G3b (n = 33), G4 (n = 43), and G5 (nondialysis) (n = 14) (age [mean +/- SD] 65.4 +/- 9.0 years, estimated glomerular filtration rate [eGFR] 26.1 +/- 9.6 ml/min per 1.73 m(2), and HbA1c 7.4 +/- 0.8%). CGM metrics were estimated from blinded CGM (Medtronic Ipro2 with Enlite sensor) and compared with HbA1c in the same week. Results: Correlations between glucose management indicator (GMI) and HbA1c attenuated with advancing CKD (G3b [r = 0.68, P < 0.0001], G4 [r = 0.52, P < 0.001], G5 [r = 0.22, P = 0.44], P = 0.01 for CKD stage). In G3b and G4, HbA1c correlated significantly with time-in-range (TIR) (3.9-10.0 mmol/l) (r = -0.55 and r = -0.54, respectively) and % time > 13.9 mmol/l (r = 0.53 and r = 0.44, respectively), but not in G5. HbA1c showed no correlation with % time < 3.0 mmol/l (r = -0.045, P = 0.67) or % coefficient of variation (CV) (r = -0.05, P = 0.64) in any CKD stage. Only eGFR was a significant determinant of bias for the difference between GMI and HbA1c (difference -0.28%, 95% CI [-0.52 to -0.03] per 15 ml/min per 1.73 m(2) decrement, P = 0.03). Conclusion: CGM-derived indices might serve as an adjunct to HbA1c monitoring to guide glycemic management, especially in those with eGFR < 30 ml/min per 1.73 m(2). Time in hypoglycemia and glycemic variability are relevant glycemic targets for optimization not reflected by HbA1c.

Automated summary

This study evaluated the relationship between HbA1c and CGM metrics in patients with moderate-to-advanced CKD. The correlations between glucose management indicator (GMI) and HbA1c attenuated with advancing CKD. HbA1c showed significant correlation with some CGM metrics in G3b and G4, but not in G5.