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

Table 1 Characteristics of participants in the present work

	Male (n = 22255)	Female (n = 22305)	P value
Age (yr)	42.12 ± 16.96	43.92 ± 17.71	< 0.0001
Race/ethnicity (%)			< 0.0001
Non-Hispanic White	68.87	70.50
Non-Hispanic Black	9.90	9.51
Mexican American	9.07	7.61
Other race/ethnicity	12.16	12.38
Education level (%)			< 0.0001
Less than high school	15.25	13.56
High school	22.89	21.07
More than high school	53.71	58.36
Others	8.15	7.01
Marital status			< 0.0001
Never married	22.22	17.57
Married	61.53	57.48
Divorced	10.22	19.85
Others	6.03	5.10
Smoked at least 100 cigarettes in life (%)			< 0.0001
Yes	48.27	37.03
No	44.76	56.91
Others	6.97	6.06
Body mass index (kg/m2)	27.91 ± 5.70	27.95 ± 7.01	0.4535
Alanine aminotransferase (U/L)	29.29 ± 22.06	20.74 ± 20.30	< 0.0001
Serum creatinine (μmol/L)	85.93 ± 26.19	66.31 ± 18.96	< 0.0001
Blood glucose (mmol/L)	5.08 ± 0.61	4.95 ± 0.59	< 0.0001
Total protein (g/L)	72.34 ± 4.53	71.24 ± 4.62	< 0.0001
Uric acid (μmol/L)	361.26 ± 72.02	277.45 ± 68.64	< 0.0001
Cholesterol (mmol/L)	5.0 ± 1.1	5.1 ± 1.1	< 0.0001
White blood cell count (109/L)	7.10 ± 2.30	7.30 ± 2.21	< 0.0001
Red blood cell count (1012/L)	4.99 ± 0.41	4.48 ± 0.36	< 0.0001
Platelet count (109/L)	240.75 ± 57.14	266.28 ± 64.99	< 0.0001
Hemoglobin (g/dL)	15.28 ± 1.02	13.64 ± 0.93	< 0.0001
Hemoglobin A1c (%)	5.34 ± 0.36	5.32 ± 0.37	< 0.0001

Data are show in mean ± SD, including age, body mass index, alanine aminotransferase, cholesterol, creatinine, blood glucose, red/white blood cell count, platelet count, total protein, serum uric acid, hemoglobin, and hemoglobin A1c. Weighted linear regression model was employed to compute the P value. Categorical variables are represented in percentage (%), including race, educational level, marital status, smoking (> 100 cigarettes in life), while weighted chi-square test was employed to compute the P value.