Hemoglobin A(1c) and fructosamine for assessing glycemic control in diabetic patients with CKD stages 3 and 4.

BACKGROUND

Hemoglobin A(1c) (HbA(1c)) and fructosamine can be used to monitor glycemic control in diabetic patients with normal kidney function, but their validity in patients with chronic kidney disease (CKD) has not been evaluated. In this study, we evaluated the correlation and accuracy of these 2 measures of glycemic control in type 2 diabetic patients with CKD stages 3-4.

STUDY DESIGN

Diagnostic test study.

SETTING & PARTICIPANTS: Type 2 diabetic patients with normal (n = 30) and abnormal kidney function (n = 30) were recruited in Taipei Veterans General Hospital, Taiwan.

INDEX TESTS

HbA(1c) and fructosamine.

REFERENCE TEST

Self-monitoring of blood glucose levels.

MEASUREMENTS

Blood glucose measurements consisted of 6 preprandial, 6 postprandial, and 2 bedtime assessments in a week with a cycle of 4-week intervals for 12 weeks.

RESULTS

Correlation coefficients between HbA(1c) level or fructosamine-albumin ratio and mean blood glucose levels were 0.836 and 0.645 in participants with normal kidney function and 0.813 and 0.649 in participants with CKD stages 3-4, respectively. In patients with CKD stages 3-4, mean blood glucose levels in weeks 1-12 were 21.9 mg/dL (95% CI, 11.6-32.5) higher than estimated average glucose (eAG) levels calculated from HbA(1c) levels in participants with normal kidney function. In patients with CKD stages 3-4, mean blood glucose levels in weeks 10-12 were 15.5 mg/dL (95% CI, 5.2-30.5) higher than eAG levels calculated from fructosamine levels in participants with normal kidney function, but without statistical significance when eAG calculated from fructosamine level was corrected for serum albumin level (difference of 5.6 mg/dL; 95% CI, -8.6 to 19.8).

LIMITATIONS

Relatively small number of participants with limited amount of blood glucose measurement data.

CONCLUSION

Our data show that eAG calculated from HbA(1c) and fructosamine levels might underestimate mean blood glucose levels in patients with CKD stages 3-4. References ranges may need to be modified when interpreting results of measurements of glycemic control in type 2 diabetic patients with CKD.