Estimated Plasma Glucose from Hemoglobin A1c of Diabetic Patients at Lampang Hospital

Objective: To study the correlation between fasting plasma glucose and hemoglobin A1c, and to investigate whether fasting plasma glucose can be used as appropriate index for glycemic control in diabetic patient. Methods: The retrospective study of fasting plasma glucose and hemoglobin A1c from diabetic patients recorded during 2009-2011 was performed. Total of 31,822 pairs of laboratory data from samples taken and analyzed on the same day using the same analytical method for plasma glucose and hemoglobin A1c were obtained from the LIS of Lampang hospital. The SPSS program was used for data analysis. Results: Correlation coefficient between fasting plasma glucose and hemoglobin A1c was 0.77 (p<0.01). The data from samples with low plasma glucose but high level of hemoglobin A1c was as high as 72.11%. The average plasma glucose estimated from hemoglobin A1c and the observed fasting plasma glucose were significantly different (p<0.001). Conclusion: This study illustrated moderate correlation between fasting plasma glucose and hemoglobin A1c in diabetic patients. Low fasting plasma glucose, but high level of hemoglobin A1c was observed in high proportion of samples. It seems that some of the low level in fasting plasma glucose can mislead physician. Therefore, estimated plasma glucose should be reported along with hemoglobin A1c result of diabetic patients.