Table 2.

Models for estimated HbA1c calculation

Models	Formulas	Correlation coefficient	p value
Model 1: original EA1c	$\text{EA1c}\%=\left(MG\text{mmol}/L+2.590\right)/1.590$	0.822	< 0.001
Model 2: linear regression in all patients with MG only	$\text{EA1c}\%=\text{MG}\times 0.483+3.300$	0.819	< 0.001
Model 3: exponential equation in all patients with MG only	$\text{EA1c}\%=-12.93\times \text{EXP}\left(-0.069\times \text{MG}\right)+14.67$	0.817	< 0.001
Model 4: quadratic equation in all patients with MG only	$\text{EA1c}\%=2.176+0.748\times \text{MG}-0.0148\times {\text{MG}}^2$	0.817	< 0.001
Model 5: linear regression in all patients	$\text{EA1c}\%=\text{MG}\times 0.258+0.217\times 4^{\text{th}}\text{MG}+3.339$	0.832	< 0.001
Model 6: linear regression in the half of patients with high MG (MG > 8.2 mmol/L)	$\begin{array}{c}\text{EA1c}\%=4^{\text{th}}\text{MG}\times 0.321+4.\text{958 when}\text{MG}>8.\text{2 mmol}/\text{L};\hfill \\ \text{EA1c}\%=\left(\text{MG}+2.590\right)/1.590\text{when}\text{MG}\le 8.\text{2 mmol}/\text{L}\hfill \end{array}$	0.825	< 0.001
Model 7: linear regression in the quarter of patients with the highest MG (patients with MG > 9.7 mmol/L)	$\begin{array}{c}\text{EA1c}\%=\text{MG}\times 0.669-0.213\times 8^{\text{th}}\text{MG}+3.\text{351 when MG}>9.\text{7 mmol}/\text{L};\hfill \\ \text{EA1c}\%=\left(\text{MG}+2.590\right)/1.590\text{when}\text{MG}\le 9.\text{7 mmol}/\text{L}\hfill \end{array}$	0.955	< 0.001

EA1c Estimated glycated hemoglobin, MG mean glucose