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Table 3 Baseline characteristics of subjects without diabetes mellitus by increased and low HbA1c levels and multivariable adjusted odds ratios for associations of characteristics with increased HbA1c levels. Pooled data from six cohort studies

From: HbA1c levels in non-diabetic older adults – No J-shaped associations with primary cardiovascular events, cardiovascular and all-cause mortality after adjustment for confounders in a meta-analysis of individual participant data from six cohort studies

Characteristic

Unit

Weighted mean or proportion (%) (95 % CI)

Pooled odds ratio (95 % CI)

Increased HbA1c

Low HbA1c

(6.0 to <6.5 %)

(5.0 to <5.5 %)

(42 to <48 mmol/mol)

(31 to <37 mmol/mol) (reference group)

Age

Years

64.5 (64.2–64.7)

62.2 (62.1–62.4)

1.41 (1.32; 1.49) per 10 years

Male sex

%

47.0 (45.2–48.7)

45.0 (44.1–46.0)

0.99 (0.88; 1.11)

Race/ethnicityb

    

 Non-Hispanic white

%

44.0

70.0

Ref

 Non-Hispanic black

%

33.8

11.8

5.92 (4.56; 7.68)

 Mexican-American

%

17.8

15.1

2.11 (1.62; 2.77)

 Other

%

4.4

3.0

2.69 (1.69; 4.28)

School education

    

 ≤9 years

%

55.6 (53.7–57.5)

45.9 (44.9–46.9)

Ref

 10–12 years

%

32.7 (30.9–34.4)

39.1 (38.1–40.0)

0.97 (0.90; 1.04)

 ≥13 years

%

14.6 (13.3–16.0)

19.0 (18.3–19.8)

0.99 (0.90; 1.08)

BMI category

    

 Underweight or low weight

%

3.2 (2.5–3.9)

3.9 (3.5–4.3)

0.81 (0.66; 0.99)

 Optimal weight

%

20.3 (18.9–21.8)

34.6 (33.7–35.5)

Ref

 Overweight

%

45.3 (43.5–47.0)

43.6 (42.7–44.6)

1.02 (0.92; 1.14)

 Obese

%

32.4 (30.8–34.1)

19.2 (18.5–20.0)

1.61 (1.43; 1.81)

Smoking

    

 Never

%

44.5 (42.7–46.3)

45.8 (44.8–46.7)

Ref

 Former

%

31.9 (30.2–33.5)

34.8 (33.9–35.7)

1.03 (0.92; 1.16)

 Current

%

24.1 (22.6–25.7)

20.0 (19.5–21.1)

1.73 (1.53; 1.96)

Relative alcohol consumption

    

 Abstainer or low

%

62.9 (61.1–64.7)

50.9 (49.9–51.9)

Ref

 Moderate

%

30.5 (28.8–32.2)

37.4 (36.4–38.3)

1.05 (0.96; 1.13)

 High

%

6.9 (6.0–7.9)

12.0 (11.4–12.7)

0.74 (0.66; 0.83)

Vigorous physical activity

%

36.0 (34.3–37.7)

42.3 (41.4–43.3)

0.93 (0.85; 1.02)

Total cholesterol

mmol/L

6.08 (6.03–6.12)

6.03 (6.01–6.05)

1.18 (1.14; 1.22) per 1 mmol/L

HDL cholesterol

mmol/L

1.36 (1.34–1.37)

1.52 (1.51–1.53)

0.62 (0.54; 0.71) per 1 mmol/L

Subclinical inflammation

%

44.7 (42.9–46.4)

28.1 (27.2–29.0)

1.47 (1.34; 1.61)

Serum creatinine

nmol/L

85.4 (84.5–86.3)

76.4 (76.0–76.8)

1.04 (1.00; 1.08) a per 10 nmol/L

Albuminuria

%

21.2 (19.6–23.0)

13.3 (12.5–14.1)

1.27 (1.11; 1.45)

Hemoglobin

g/dL

13.98 (13.92–14.04)

14.16 (14.14–14.19)

0.86 (0.77; 0.96) a per 1 g/dL

Biomarkers of iron deficiencyb

    

 Ferritin

μg/L

165 (170)

152 (148)

0.97 (0.91; 1.03) per 100 μg/L

 Transferrin saturation

%

23.8 (10.1)

26.0 (10.6)

0.85 (0.77; 0.95) per 10 %

 Erythrocyte protoporphyrin

μmol/L

0.94 (0.44)

0.93 (0.42)

1.02 (0.91; 1.15) per 0.5 μmol/L

Hypertension

    

 No hypertension

%

34.7 (33.1–36.4)

47.0 (46.1–48.0)

Ref

 Known hypertension or systolic blood pressure ≥140 to <160 mmHg

%

49.5 (47.8–51.3)

40.2 (39.3–41.1)

1.08 (1.01; 1.15)

 Systolic blood pressure ≥160 mmHg

%

17.1 (15.8–18.5)

14.0 (13.4–14.7)

1.10 (1.01; 1.20)

History of MI or stroke

%

11.8 (10.7–13.0)

7.1 (6.6–7.6)

1.32 (1.03; 1.70) a

Biomarkers of liver functionb

    

 GGT

U/L

33.5 (36.0)

29.9 (40.3)

1.02 (0.99; 1.05) per 10 U/L

 AST

U/L

21.5 (13.1)

22.0 (11.9)

0.81 (0.70; 0.94) per 10 U/L

 ALT

U/L

15.0 (11.2)

14.6 (11.3)

1.25 (1.08; 1.45) per 10 U/L

  1. The table shows pooled means or proportions of baseline characteristics in the HbA1c categories and additionally the results of a multivariable logistic regression model including all variables of the table as explanatory variables for increased HbA1c (reference: low HbA1c). Bold indicates statistically significant difference (p <0.05). aRandom effects model reported because of statistically significant heterogeneity; bassessed in NHANES, only. ALT, alanine transferase; AST, aspartate transferase; BMI, body mass index; GGT, gamma-glutamyl transferase; CI, confidence interval; HbA1c, glycated hemoglobin; HDL, high-density lipoprotein; MI, myocardial infarction