Continuous glucose monitoring (CGM) systems, including real-time CGM (rtCGM) and intermittently scanned CGM (isCGM), have shown significant efficacy in enhancing diabetes management. A recent cross-sectional study, based on the Swedish National Diabetes Register, explored the relationships between HbA1c and various CGM-derived metrics among 27,980 adults with type 1 diabetes.

      The study aimed to assess the association between HbA1c and metrics such as time in range (TIR), time above range (TAR), time below range (TBR), mean glucose, standard deviation (SD), and coefficient of variation (CV). The analysis included 46% women, 30% on insulin pumps, 7% with previous coronary heart disease, and 64% with retinopathy. The mean values for age, diabetes duration, and HbA1c were 48 ± 18 years, 25 ± 16 years, and 58.8 ± 12.8 mmol/mol, respectively. Key CGM metrics included TIR at 58.8 ± 19.0%, TAR at 36.3 ± 20.0%, TBR at 4.7 ± 5.4%, mean sensor glucose at 9.2 ± 2.0 mmol/l, SD at 3.3 ± 1.0 mmol/l, and CV at 36 ± 7%.

      The study employed Pearson correlation coefficients and linear regression models to estimate the relationships. The overall association between HbA1c and TIR was strong (Pearson’s r = -0.71), with an R² of 0.51 in crude linear regression and 0.57 in an adjusted model. R² values between HbA1c and CGM mean glucose were 0.605 (unadjusted) and 0.619 (adjusted), and for TAR, 0.554 (unadjusted) and 0.568 (adjusted). The fully adjusted R² values for the associations between HbA1c and CGM SD, CGM CV, and TBR were 0.458, 0.175, and 0.101, respectively.

      This descriptive study, published in ‘Diabetes Therapy,’ demonstrates that the association between HbA1c and CGM-derived metrics, particularly TIR, TAR, and mean glucose, is robust in evaluating diabetes management. These findings underscore the value of CGM metrics in clinical settings, offering a comprehensive view of glucose control in individuals with type 1 diabetes.

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