Table 1.
Baseline clinical and laboratory characteristics of the study population.
| HbA1c variability groups* | ||||
|---|---|---|---|---|
| 1st tertile (n = 2,136) | 2nd tertile (n = 2,199) | 3rd tertile (n = 2,127) | p | |
| HbA1c coefficient of variation | 0.0216 | 0.0392 | 0.0659 | <0.001 |
| Age, years | 50 ± 7.5 | 50 ± 7.5 | 50 ± 7.7 | 0.27 |
| Male sex | 1,011 (47.3) | 1,056 (48.0) | 1,004 (47.2) | 0.84 |
| Current smoking | 463 (22.0) | 463 (21.3) | 447 (21.2) | 0.66 |
| Hypertension | 219 (10.3) | 243 (11.1) | 300 (14.1) | <0.001 |
| Dyslipidaemia | 46 (2.2) | 54 (2.5) | 57 (2.7) | 0.53 |
| Previous MI | 13 (0.6) | 10 (0.5) | 17 (0.8) | 0.35 |
| Previous CAD | 9 (0.4) | 12 (0.5) | 15 (0.7) | 0.46 |
| Previous CKD | 60 (2.8) | 58 (2.6) | 63 (3.0) | 0.81 |
| Laboratory variables | ||||
| Total cholesterol, mg/dL | 197 ± 34 | 197 ± 35 | 197 ± 36 | 0.73 |
| Triglycerides, mg/dL | 142 ± 98 | 143 ± 99 | 149 ± 106 | 0.09 |
| HDL-cholesterol, mg/dL | 50 ± 12 | 50 ± 12 | 50 ± 12 | 0.94 |
| LDL-cholesterol, mg/dL | 118 ± 33 | 119 ± 333 | 117 ± 34 | 0.24 |
| HbA1c, % | 5.5 ± 0.3 | 5.5 ± 0.3 | 5.6 ± 0.4 | <0.001 |
| HbA1c, mmol/mol | 37 ± 2 | 37 ± 2 | 38 ± 3 | |
| High sensitivity CRP, mg/L | 1.48 ± 2.74 | 1.50 ± 2.38 | 1.60 ± 3.17 | 0.28 |
| Homocysteine, µmol/L | 11.5 ± 3.7 | 11.8 ± 4.4 | 11.8 ± 4.4 | 0.053 |
| Fasting glucose, mg/dL | 91 ± 8 | 91 ± 8 | 93 ± 10 | <0.001 |
| 3rd tertile FBG group | 596 (28.1) | 680 (31.1) | 845 (40.0) | <0.001 |
| Post-prandial glucose, mg/dL | 125 ± 30 | 126 ± 31 | 135 ± 39 | <0.001 |
| 3rd tertile PBG group | 634 (29.9) | 707 (32.3) | 771 (36.8) | <0.001 |
| Fasting insulin, µIU/mL | 7.6 ± 4.4 | 7.5 ± 4.7 | 7.5 ± 4.5 | 0.77 |
| HOMA-IR† | 1.79 ± 0.67 | 1.80 ± 0.65 | 1.94 ± 0.90 | <0.001 |
| HOMA β-cell | 108.4 ± 41.9 | 106.3 ± 42.1 | 106.9 ± 44.6 | 0.25 |
| QUICKI‡ | 0.354 ± 0.018 | 0.353 ± 0.017 | 0.350 ± 0.019 | <0.001 |
| QUICKI < 0.339 | 412 (19.3) | 416 (19.0) | 575 (27.1) | <0.001 |
| Metabolic syndrome | 374 (17.5) | 363 (16.5) | 428 (21.0) | 0.006 |
| Body composition variables | ||||
| BMI, kg/m2 | 24.4 ± 3.0 | 24.4 ± 2.8 | 26.6 ± 3.1 | 0.02 |
| Muscle mass, kg | 43.7 ± 8.1 | 44.0 ± 7.9 | 44.1 ± 8.0 | 0.33 |
| Muscle mass/BMI, m2 | 1.80 ± 0.33 | 1.81 ± 0.33 | 1.78 ± 0.33 | 0.01 |
| Fat mass, kg | 16.8 ± 5.3 | 16.7 ± 5.1 | 17.1 ± 5.4 | 0.08 |
| Fat mass/BMI, m2 | 0.68 ± 0.16 | 0.68 ± 0.16 | 0.68 ± 0.16 | 0.42 |
Values are presented as number (%) for categorical variables and mean ± standard deviation (SD) for continuous variables.
CAD, coronary artery disease; CKD, chronic kidney disease; CRP, C-reactive protein; FBG, fasting blood glucose; HbA1c, glycated haemoglobin; HDL, high-density lipoprotein; HOMA-IR, homeostatic model assessment of insulin resistance; LDL, low-density lipoprotein; MI, myocardial infarction; OGTT, oral glucose tolerance test; PBG, post 2-h blood glucose; QUICKI, quantitative insulin sensitivity check index.
*HbA1c variability was assessed using the coefficient of variation for all HbA1c measurements throughout the study. †HOMA-IR = (fasting insulin, µIU/mL) × (fasting glucose, mmol/L)/22.5; HOMA β-cell = [20 × (fasting insulin, µIU/mL)]/[(fasting glucose, mmol/L) − 3.5] (reference 15). ‡QUICKI = 1/[log (fasting insulin, µIU/mL) + log (fasting glucose, mg/dL)] (ref.16).