Issue 125 Item 11 Hemoglobin Glycation Phenotype May Be Important For Clinical A

The hemoglobin glycation phenotype of diabetics may be important for assessing their blood glucose control. Researchers at the Louisiana State University Health Sciences Center, in New Orleans, Louisiana, United States, have determined that there are consistent individual differences in the relationship between glycated hemoglobin (HbA1c) and mean blood glucose levels in individuals with similar preceding blood glucose levels.

James M. Hempe, PhD, and his colleagues collected blood glucose data for up to 2.3 years from 128 children and adolescents with type I diabetes. The patients’ HbA1c values were date-matched with mean blood glucose levels calculated from an average of 85 self-monitored blood glucose measurements collected over the previous 30 days.

The researchers found a significant linear correlation between mean blood glucose and HbA1c levels, but also noted a wide variability in the population HbA1c response to mean blood glucose.

They calculated a hemoglobin glycation index (HGI=observed HbA1c-predicted HbA1c) to quantify the magnitude and direction of the difference between each patient’s set of observed and predicted HbA1c results.

Likelihood ratio tests and t statistics showed that the mean hemoglobin glycation index were significantly different among individuals, and that 29 percent of the patients had HbA1c levels that were statistically significantly higher or lower than predicted by the regression equation, the researchers reported.

The observed individual differences in the relationship between mean blood glucose and HbA1c were not related to erythrocyte age and there was no evidence of analytical artifact.

"We interpret these results as possible evidence of high and low hemoglobin glycation phenotypes within the population," the investigators wrote. "We conclude that mean blood glucose and HbA1c are not necessarily interchangeable estimates of glycemic control and that hemoglobin glycation phenotype may be important for the clinical assessment of diabetic patients."
J Diabetes Complications 2002; 16: 313-320