Subgroup analyses for studies reporting adjusted effect estimates
| Subgroups | No. of studies | OR (95% CI) | P value | I2 | P value for within-stratum heterogeneity | P value for between-stratum heterogeneity |
| Compared groups | ||||||
| Insulin versus oral drugs | 6 | 1.42 (1.08 to 1.86) | <0.05 | 71.3% | <0.05 | 0.28 |
| Insulin versus non-drugs | 2 | 0.87 (0.37 to 2.03) | >0.05 | 66.5% | 0.08 | |
| Degree of adjustment | ||||||
| +++ | 10 | 1.43 (1.08 to 1.89) | <0.05 | 68.9% | <0.05 | 0.44 |
| ++ | 2 | 1.24 (0.98 to 1.55) | >0.05 | 25.3% | 0.25 | |
| Region | ||||||
| USA | 4 | 0.86 (0.57 to 1.31) | >0.05 | 36.4% | 0.19 | 0.12 |
| Asia | 5 | 1.81 (1.18 to 2.79) | <0.05 | 59% | 0.05 | |
| Europe | 2 | 1.58 (0.85 to 2.94) | >0.05 | 92.9% | <0.05 | |
| Africa | 1 | 1.53 (0.99 to 2.37) | >0.05 | – | – | |
| Identification of depression | ||||||
| Self-report questionnaire | 10 | 1.42 (1.06 to 1.91) | <0.05 | 68.9% | <0.05 | 0.69 |
| Medical records | 2 | 1.31 (1.00 to 1.71) | >0.05 | 65.6% | 0.09 | |
| Sample size | ||||||
| ≥1000 | 4 | 1.46 (1.10 to 1.94) | <0.05 | 73.1% | <0.05 | 0.72 |
| <1000 | 8 | 1.34 (0.93 to 1.93) | >0.05 | 70% | <0.05 | |
| Mean age, years | ||||||
| ≥60.0 | 5 | 1.12 (0.77 to 1.62) | >0.05 | 78.8% | <0.05 | 0.08 |
| <60.0 | 6 | 1.74 (1.24 to 2.43) | <0.05 | 50.8% | 0.07 | |
| Percentage male (%) | ||||||
| ≥50.0 | 7 | 1.26 (0.97 to 1.63) | >0.05 | 62.4% | <0.05 | 0.14 |
| <50.0 | 5 | 1.71 (1.25 to 2.35) | <0.05 | 53.9% | 0.07 | |
| Prevalence of depression | ||||||
| ≥20% | 7 | 1.48 (1.12 to 1.96) | <0.05 | 71.3% | <0.05 | 0.53 |
| <20% | 5 | 1.25 (0.80 to 1.95) | >0.05 | 72.7% | <0.05 | |
| NOS | ||||||
| 7 or 8 | 8 | 1.25 (0.94 to 1.66) | >0.05 | 60.0% | <0.05 | 0.19 |
| <7 | 4 | 1.79 (1.14 to 2.80) | <0.05 | 84.6% | <0.05 | |
NOS, Newcastle-Ottawa Scale.