Table 1. Characteristics of twins at baseline and summary of follow-up outcomes according to the quintile of postload glucose levelsa.
| Variable | Quintile of Postload Plasma Levels of Glucose (mmol/L) | ||||||
| Entire Cohort(N = 903) | [50, 112](N = 181) | [113, 136](N = 180) | [137, 156](N = 177) | [158, 185](N = 183) | [186, 250](N = 182) | p valueb | |
| Baseline characteristics | |||||||
| Postload glucose (mmol/L) | 8.3 (2.3) | 5.2 (0.78) | 6.9 (0.39) | 8.2 (0.44) | 9.6 (0.4) | 11.7 (0.94) | <.001 |
| Age (y) | 47.7 (3.1) | 47.5 (3.4) | 47.5 (3.1) | 47.7 (3.2) | 48.1 (2.9) | 48.4 (3.0) | .35 |
| Smoking (n,%) | .047 | ||||||
| Never smokers | 377 (41.7) | 72 (39.8) | 70 (38.9) | 72 (40.7) | 76 (41.5) | 87 (47.8) | |
| Former smokers | 82 (9.1) | 13 (7.2) | 19 (10.6) | 17 (9.6) | 10 (5.5) | 23 (12.6) | |
| Current smokers | 444 (49.2) | 96 (53.0) | 91 (50.6) | 88 (49.7) | 97 (53.0) | 72 (39.6) | |
| Marital status (n, %) | .81 | ||||||
| Never married | 50 (5.6) | 7 (3.9) | 14 (7.9) | 10 (5.7) | 10 (5.5) | 9 (5.0) | |
| Not married currently | 52 (5.8) | 7 (3.9) | 15 (8.5) | 12 (6.8) | 10 (5.5) | 8 (4.4) | |
| Married currently | 794 (88.6) | 166 (92.2) | 148 (83.6) | 154 (87.5) | 162 (89.0) | 164 (90.6) | |
| Education (y) | 13.1 (2.9) | 13.2 (2.9) | 13.1 (3.0) | 12.7 (2.9) | 13.1 (2.9) | 13.3 (2.8) | .47 |
| Body mass index (kg/m2) | 25.6 (3.1) | 25.1 (2.7) | 25.7 (2.8) | 25.4 (2.9) | 25.8 (3.4) | 26.2 (3.7) | .001 |
| Systolic blood pressure (mm Hg) | 127 (16) | 121 (14) | 125 (15) | 127 (17) | 129 (15) | 132 (18) | <.001 |
| Low-density lipoprotein cholesterol (mmol/L) | 3.70 (0.9) | 3.78 (0.9) | 3.72 (0.8) | 3.70 (0.9) | 3.62 (0.9) | 3.72 (1.0) | .19 |
| High-density lipoprotein cholesterol (mmol/L) | 1.19 (0.4) | 1.16 (0.4) | 1.14 (0.3) | 1.19 (0.4) | 1.19 (0.4) | 1.21 (0.4) | .60 |
| Triglyceride (mmol/L) | 1.21 (0.85–1.75) | 1.07 (0.81–1.48) | 1.12 (0.88–1.60) | 1.26 (0.88–1.82) | 1.26 (0.85–1.77) | 1.38 (0.88–2.25) | .001 |
| High-density lipoprotein cholesterol/triglyceride | 0.41 (0.26–0.64) | 0.46 (0.31–0.64) | 0.42 (0.27–0.63) | 0.39 (0.25–0.63) | 0.37 (0.26–0.64) | 0.35 (0.20–0.70) | .02 |
| Use of antihypertensives | 48 (5.3) | 3 (1.7) | 13 (7.2) | 7 (4.0) | 9 (4.9) | 16 (8.8) | .014 |
| Summary of follow-up outcomes | |||||||
| Person-years (y) | 26309 | 5419 | 5403 | 5094 | 5437 | 4957 | |
| No. of deaths | |||||||
| Coronary heart disease | 93 | 7 (7.5) | 15 (16) | 27 (29) | 19 (20) | 25 (27) | .0013 |
| Cardiovascular disease | 172 | 22 (13) | 27 (16) | 39 (23) | 38 (22) | 46 (27) | <.001 |
| All causes | 588 | 112 (19) | 113 (19) | 112 (19) | 121 (21) | 130 (22) | .013 |
a
Values are means (standard deviation) for continuous variables, n (%) for categorical variables, or median (25th–75th percentile) for skewed-distributed variables unless otherwise indicated.
b
Test for trend across the quintile of postload glucose levels at 1-hour after a 50-gram glucose load. All p values are corrected for clustering within a twin pair according to the twin type using linear mixed models for continuous variables, and generalized estimating equation logistic models for dichotomous variables, and repeated proportional odds model with generalized estimating equation for the 3-level smoking, and marital status variables. Raw values for continuous variables are presented.