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Table 1 Pooled estimated effect of placebo response in patients with diabetes mellitus

From: Age, sex, disease severity, and disease duration difference in placebo response: implications from a meta-analysis of diabetes mellitus

Variables No. of trials HbA1c change (%) Weight change (kg)
Pooled ES 95% CI P value I2 (%) Pooled ES 95% CI P value I2 (%)
Types of diabetes mellitus
 Diabetes in total 433 − 0.11 − 0.15, − 0.07 < 0.01 88 − 0.30 − 0.40, − 0.20 < 0.01 71
 Type 1 diabetes 41 − 0.06 − 0.13, 0.02 0.16 74 0.33 0.03, 0.62 0.03 70
 Type 2 diabetes 392 − 0.12 − 0.16, − 0.07 < 0.01 89 − 0.40 − 0.50, − 0.29 < 0.01 67
Treatment design
 Monotherapy 148 0.08 0.01, 0.16 0.02 79 − 0.56 − 0.73, − 0.39 < 0.01 63
 Add-on therapy 285 − 0.20 − 0.25, − 0.15 < 0.01 89 − 0.19 − 0.32, − 0.07 < 0.01 71
Administration route
 Oral total 355 − 0.08 − 0.13, − 0.04 < 0.01 88 − 0.30 − 0.41, − 0.19 < 0.01 61
 Injection total 78 − 0.21 − 0.30, − 0.12 < 0.01 88 − 0.30 − 0.53, − 0.07 0.01 84
Type 1 diabetes
 Oral 31 0.01 − 0.10, 0.12 0.84 73 0.25 − 0.13, 0.63 0.20 63
 Injection 10 − 0.16 − 0.27, − 0.04 < 0.01 75 0.41 − 0.03, 0.85 0.07 77
Type 2 diabetes
 Oral 324 − 0.09 − 0.14, − 0.04 < 0.01 89 − 0.37 − 0.48, − 0.25 < 0.01 58
 Injection 68 − 0.22* − 0.32, − 0.11 < 0.01 88 − 0.46 − 0.70, − 0.22 < 0.01 82
Comparator agent type
Type 1 diabetes
 Metformin 13 0.21 − 0.06, 0.48 0.13 72 0.71 − 0.29, 1.70 0.17 37
 AGI 2 0.01 − 0.36, 0.38 0.97 82 − 0.63 − 2.10, 0.84 0.40 94
 TZD 4 − 0.60 − 1.37, 0.18 0.13 0 1.21 − 6.52, 8.94 0.76 0
 DPP-4i 1 − 0.12 − 1.59, 1.35 0.87 NA 0.02 − 5.21, 5.25 0.99 NA
 GLP-1RA 5 − 0.26 − 0.44 -0.07 < 0.01 56 0.41 − 0.27, 1.08 0.24 45
 SGLT2i 11 − 0.09 − 0.20, 0.02 0.10 75 0.39 0.08, 0.70 0.01 36
 Pramlintide 5 − 0.09 − 0.23, 0.05 0.20 79 0.41 − 0.17, 0.99 0.17 85
Type 2 diabetes
 Metformin 23 0.14†‡ − 0.05, 0.33 0.14 59 − 0.57 − 0.93, − 0.21 < 0.01 0
 AGI 40 − 0.01 − 0.24, 0.22 0.91 89 − 0.17 − 0.51, 0.16 0.31 0
 TZD 64 0.07†‡ − 0.09, 0.24 0.39 76 − 0.17 − 0.66, 0.32 0.50 35
 SU 24 0.05 − 0.19, 0.29 0.68 70 − 0.48 − 1.96, 1.00 0.53 78
 DPP-4i 95 − 0.11 − 0.20, − 0.02 0.01 92 − 0.32 − 0.49, − 0.14 < 0.01 67
 GLP-1RA 68 − 0.22 − 0.32, − 0.11 < 0.01 88 − 0.46 − 0.70, − 0.22 < 0.01 82
 SGLT2i 78 − 0.26 − 0.35, − 0.17 < 0.01 90 − 0.42 − 0.60, − 0.24 < 0.01 60
  1. Font bold was used if P < 0.05 was noticed
  2. ES effect size, SU sulfonylurea, AGI alpha glucosidase inhibitor, TZD thiazolidinedione, DPP-4 dipeptidyl peptidase-4, SGLT2 sodium-glucose cotransporter 2, GLP-1RA glucagon-like peptide-1 receptor agonist
  3. *Compared with oral subgroup, P < 0.05
  4. Compared with GLP-1RA group, P < 0.05
  5. Compared with SGLT2i group, P < 0.05