Hemoglobin within normal range is negatively related to hemoglobin A1c in a nondiabetic American population aged 16 years and older

Table 4 Threshold effect analysis of hemoglobin-on-hemoglobin A1c using piecewise linear regression

Point of hemoglobin (g/dL)	Odd ratio (95%CI)	P value
< 13.2	-0.04 (-0.05, -0.03)	< 0.0001
> 13.2	-0.10 (-0.10, -0.09)	< 0.0001

A threshold of 13.2g/dL for the hemoglobin existed for hemoglobin A1c. Parameters were adjusted, including age, race, body mass index, smoking (> 100 cigarettes in life), educational level, marital status, serum uric acid, alanine aminotransferase, creatinine, blood glucose, total protein, cholesterol, red/white blood cell count, and platelet count.