Cessation of menstruation improves the correlation of FPG to hemoglobin A1c in Caucasian women.

Abstract

Anemia is known to cause spurious hemoglobin A1c (HbA1c) results. The effect of menstruation on HbA1c was tested by correlating it to FPG in non-anemic premenopausal and in menopausal women. Non-diabetic, non-obese middle-aged Caucasian women were classified as premenopausal or menopausal. Hemogram, FPG, and A1c results were obtained. Hemoglobin concentrations were lower in the premenopausal group. FPG showed a poor correlation to A1c value overall (r = 0.251, p = 0.001) which was improved by multiplying the A1c % by the total hemoglobin concentration to create an absolute A1c value (r = 0.362, p = 0.000). When the data was sorted by menopause status, the correlation of FPG to Absolute A1c improved (r = 0.463, p = 0.000) in the menopausal women, but remained low (r = 0.283, p = 0.005) in the premenopausal women. Menstruation may be a significant factor affecting the accuracy of A1c concentrations.