Table 2

Changes in primary and secondary outcomes and process variables

OverallInterventionControlBetween-group differenceP value*Effect size (95% CI)
Primary outcomeBaseline n = 81Baseline n = 41Follow-up n = 38Change n = 38Baseline n = 40Follow-up n = 37Change n = 37
 HbA1c10.8 (1.9)11.0 (2.0)10.5 (2.4)−0.6 (1.7)10.5 (1.7)10.8 (2.2)0.4 (1.6)0.90.01−0.5 (−0.9, −0.1)
Secondary outcomesBaseline n = 41Follow-up n = 35Change n = 35Baseline n = 40Follow-up n = 37Change n = 37
 Diabetes-related QOL (ADDQOL; range −9 to +1)−2.6 (1.7)−2.4 (1.8)−1.8 (1.7)0.7 (1.1)−2.8 (1.7)−2.5 (1.6)0.2 (1.5)0.50.040.3 (−0.1, 0.7)
 Glucose monitoring (days/week) (SDSCA; range 0–7)3.3 (2.7)3.1 (2.7)4.0 (2.6)0.6 (3.2)3.5 (2.7)3.6 (2.5)−0.1 (2.7)0.70.370.3 (−0.2, 0.8)
 Medication adherence (days/week) (SDSCA; range 0–7)5.9 (1.8)5.7 (2.2)6.3 (1.2)0.3 (1.8)6.0 (1.3)6.2 (1.5)0.1 (1.4)0.20.930.1 (−0.3, 0.5)
 Diabetes distress (PAID-SF; range 0–20)9.6 (5.7)9.7 (5.2)7.4 (6.0)−2.6 (4.3)9.4 (6.2)7.5 (4.9)−1.7 (4.6)0.80.26−0.1 (−0.5, 0.2)
 Life satisfaction (SWLS; range 5–35)20.5 (6.8)20.3 (6.1)23.0 (5.9)2.6 (5.2)20.7 (7.4)22.2 (7.3)1.4 (4.4)1.20.210.2 (−0.2, 0.5)
 Depressive symptoms (PHQ-8; range 0–27)6.9 (5.0)6.6 (5.3)5.4 (5.0)−0.9 (4.1)7.2 (4.7)6.9 (5.6)−0.0 (4.5)0.90.42−0.2 (−0.6, 0.2)
Process variablesBaseline n = 41Follow-up n = 35Change n = 35Baseline n = 40Follow-up n = 37Change n = 37
 Diabetes knowledge (DKQ; range 0–24)18.1 (3.2)18.2 (3.0)18.9 (2.4)0.6 (1.9)17.9 (3.5)18.2 (3.4)0.2 (1.6)0.30.500.1 (−0.2, 0.4)
 Problem-solving (DPSI; range 1–5)3.6 (0.6)3.6 (0.8)3.7 (0.6)0.1 (0.6)3.6 (0.5)3.9 (0.5)0.3 (0.5)0.20.10−0.3 (−0.7, 0.1)
 Diabetes self-efficacy (DES-SF; range 1–5)3.9 (0.7)3.9 (0.7)4.1 (0.8)0.2 (0.9)3.9 (0.7)3.9 (1.0)0.0 (0.9)0.20.270.2 (−0.4, 0.9)
 Habit strength
  Glucose monitoring (SRBAI; range 4–28)15.0 (6.9)13.9 (6.7)18.3 (6.2)3.9 (5.0)16.2 (6.9)18.1 (6.8)1.6 (5.1)2.30.050.3 (−0.2, −0.7)
  Medication adherence (SRBAI; range 4–28)19.0 (6.3)17.9 (7.0)20.6 (6.2)2.1 (6.0)19.6 (5.7)20.9 (5.6)1.0 (6.8)1.20.320.2 (−0.3, 0.7)
 Participation
  Objective (POPS; range: weighted z scores −3 to 3)−0.0 (0.2)−0.0 (0.3)−0.0 (0.3)0.0 (0.3)−0.1 (0.2)−0.1 (0.2)−0.0 (0.2)0.00.560.1 (−0.3, 0.5)
  Subjective (POPS; range −4 to +4)−0.0 (0.1)−0.1 (1.0)0.2 (1.0)0.3 (1.1)−0.1 (0.8)0.3 (0.6)0.3 (0.7)0.00.95−0.0 (−0.6, 0.5)
  • *Wilcoxon rank sum test for change difference between treatment groups.

  • †We provide Cohen d effect sizes as a well-recognized measure of the strength of intervention effects. It should be noted, however, that these effect sizes are based on the assumption of a normally distributed variable and are not necessarily fully consistent with the nonparametric Wilcoxon method that was used to calculate P values.