Table 4.
Mean values of secondary outcomes at baseline and follow-up after a diabetes prevention intervention
| Outcome variable | Group | Baseline mean (SD)a | 6 months mean (SD)b | 12 months mean (SD)b | 18 months mean (SD)b | RM ANOVA Group visit Interaction p-valuec | RM ANOVA Effect of visit p-valued |
|---|---|---|---|---|---|---|---|
| Fruit intake (servings/day) | Intervention | 1.03 (0.73) | 1.27 (0.86) | 1.23 (0.88) | 1.31 (0.92) | 0.002 | |
| Control | 1.12 (0.85) | 1.17 (0.96) | 1.08 (0.85) | 1.12 (0.95) | |||
| Total sugar intake (g/day) | Intervention | 116.2 (86.8) | 83.0 (60.4) | 89.7 (63.9) | 90.4 (75.5) | 0.18 | <0.001 |
| Control | 109.8 (71.9) | 97.2 (60.5) | 84.9 (63.5) | 93.4 (58.9) | |||
| Sweetened beverages (oz/day) | Intervention | 22.2 (21.5) | 15.9 (16.6) | 16.3 (17.4) | 16.9 (17.7) | 0.26 | <0.001 |
| Control | 20.5 (18.1) | 19.3 (18.9) | 15.7 (15.8) | 17.5 (18.6) | |||
| Television viewing (hrs/day) | Intervention | 2.42 (1.80) | 2.02 (1.46) | 1.96 (1.54) | 2.03 (1.55) | 0.89 | <0.001 |
| Control | 2.54 (1.99) | 2.08 (1.56) | 1.98 (1.48) | 2.00 (1.76) | |||
| Control | 92.84 (8.95) | 93.78 (9.62) | 92.74 (9.25) | 92.86 (8.78) | |||
| Fasting blood glucose (mmol/l) | Intervention | 5.20 (0.46) | 5.14 (0.43) | 5.17 (0.49) | 5.12 (0.54) | 0.21 | 0.47 |
| Control | 5.16 (0.50) | 5.21 (0.53) | 5.15 (0.51) | 5.16 (0.49) | |||
| Insulin sensitivity (QUICKI) | Intervention | 0.33 (0.03) | 0.33 (0.03) | 0.33 (0.03) | 0.33 (0.03) | 0.76 | 0.001 |
| Control | 0.33 (0.03) | 0.33 (0.03) | 0.33 (0.03) | 0.32 (0.03) | |||
| BMI (kg/m2) d | Intervention | 29.5 (5.9) | 29.4 (5.8) | 29.4 (6.0) | 29.4 (6.0) | 0.08 | 0.58 |
| Control | 29.2 (6.7) | 29.3 (6.3) | 29.5 (6.4) | 29.6 (6.5) | |||
| Body fat (%) | Intervention | 41.6 (6.3) | 41.8 (6.4) | 42.1 (6.3) | 42.3 (6.4) | 0.66 | <0.001 |
| Control | 40.8 (6.6) | 41.2 (6.3) | 41.5 (6.2) | 41.6 (6.2) | |||
| Waist circumference (cm) | Intervention | 93.3 (14.7) | 92.1 (14.3) | 91.7 (14.6) | 91.9 (14.7) | 0.77 | <0.001 |
| Control | 91.8 (15.6) | 90.8 (14.4) | 90.9 (15.0) | 90.5 (15.5) | |||
| Systolic blood pressure (mmHg) | Intervention | 115.8 (13.2) | 115.3 (13.7) | 114.4 (13.1) | 114.9 (12.2) | 0.72 | 0.81 |
| Control | 116.6 (11.2) | 116.9 (14.3) | 116.7 (14.1) | 117.0 (14.0) | |||
| Diastolic blood pressure (mmHg) | Intervention | 67.6 (10.8) | 66.1 (10.0) | 68.0 (10.4) | 67.9 (9.3) | 0.06 | 0.82 |
| Control | 68.7 (9.4) | 69.9 (10.6) | 69.1 (10.4) | 68.8 (9.7) | |||
| Peak VO2 (L/min) | Intervention | 2.08 (0.45) | 2.05 (0.43) | 2.06 (0.41) | 2.05 (0.40) | 0.93 | 0.13 |
| Control | 1.20 (0.41) | 1.94 (0.36) | 1.98 (0.39) | 1.94 (0.38) | |||
| Total cholesterol (mmol/l) | Intervention | 4.34 (0.81) | 4.20 (0.78) | 4.20 (0.79) | 4.18 (0.78) | 0.60 | <0.001 |
| Control | 4.36 (0.65) | 4.28 (0.62) | 4.22 (0.69) | 4.27 (0.64) | |||
| LDL (mmol/l) e | Intervention | 2.42 (0.65) | 2.28 (0.66) | 2.26 (0.63) | 2.28 (0.61) | 0.88 | <0.001 |
| Control | 2.38 (0.52) | 2.28 (0.51) | 2.23 (0.56) | 2.27 (0.57) | |||
| HDL (mmol/l) e | Intervention | 1.26 (0.31) | 1.26 (0.30) | 1.29 (0.33) | 1.26 (0.29) | 0.94 | 0.03 |
| Control | 1.31 (0.31) | 1.30 (0.27) | 1.34 (0.32) | 1.30 (0.29) | |||
| Triglycerides (mmol) | Intervention | 1.46 (0.64) | 1.44 (0.68) | 1.41 (0.60) | 1.40 (0.68) | 0.24 | 0.18 |
| Control | 1.46 (3.15) | 1.52 (0.68) | 1.40 (0.57) | 1.52 (0.72) |
Baseline means statistically equivalent between groups (all p>0.10 per student t-test). n=96 for the Intervention group and n=95 for the Control group for fruit intake; for peak VO2 n=98 at baseline and 6 months for Intervention group, and n=99 for 12 months and 18 months for Intervention group and for all time points for Control group; n=100 per group for all other variables.
Missing data due to dropping out of the study were addressed by applying intention to treat (last value carried forward). Remaining missing data were interpolated by averaging the adjacent values.
Repeated measures analyses of variance (RM ANOVA) model for each outcome variable with Group (intervention versus control) as a grouping variable, visit as a repeated factor and with group by visit interaction term.
If group by visit interaction was not significant, then additive RM ANOVA model with Group (Intervention versus Control) as a grouping variable and visit as the repeated variable.
BMI=body mass index; LDL=low-density lipoprotein cholesterol; HDL=high-density lipoprotein cholesterol.