Associations of Hemoglobin Glycation Index with Glucose Variability and Time in Ranges in Patients with Type 2 Diabetes Undergoing Continuous Glucose Monitoring.

BACKGROUND: Discordance between glycated hemoglobin (HbA1c) levels and blood glucose is commonly observed in clinical practice. The hemoglobin glycation index (HGI) has been proposed as a measure to quantify individual variations in glycation. Our study aimed to investigate the association between HGI and glucose variability assessed by continuous glucose monitoring (CGM) in patients with type 2 diabetes (T2D) treated with metformin monotherapy. METHODS: Adults with T2D treated with metformin monotherapy (daily dose ≥ 1500 mg) who had HbA1c levels ≥ 7.0% (n = 100; mean age 54.0 ± 8.2 years; 52.0% female) undergoing CGM were analyzed. Predicted HbA1c was derived from linear regression of HbA1c on fasting plasma glucose, and the HGI was calculated as observed HbA1c minus predicted HbA1c. CGM metrics-including standard deviation, coefficient of variation, mean amplitude of glycemic excursions (MAGE), and time in ranges-were analyzed to evaluate their associations with HGI. RESULTS: HGI was significantly associated with mean sensor glucose (β = 13.60, 95% CI 5.16-22.04, p = 0.002) and CGM-derived glucose variability metrics, including standard deviation (β = 7.53, 95% CI 4.49-10.58, p < 0.001), coefficient of variation (β = 2.22, 95% CI 0.29-4.15, p = 0.025), and MAGE (β = 22.14, 95% CI 14.59-29.69, p < 0.001). These associations remained significant after multivariable adjustment. HGI was also negatively associated with time in range (β = -7.29, 95% CI -12.79 to -1.79, p = 0.010) and positively associated with time above range (β = 7.35, 95% CI 1.69-13.01, p = 0.011). CONCLUSION: These findings highlight a significant association between HGI and glucose variability from CGM, suggesting that HGI may serve as a complementary marker in diabetes management.