Table 2.
Diabetes medication classes and breast cancer risk.
| RR 95% CI | P value for effect | P value for Egger's test | I2 (%) | P value for difference between subgroups | ||
|---|---|---|---|---|---|---|
| Biguanides | ||||||
| All studies (n = 8) | 0.74 (0.47–1.17) | 0.20 | 0.96 | 99.08 | – | |
| Study design | Cohort (n = 6) | 0.69 (0.39–1.22) | 0.21 | – | 99.01 | 0.37 |
| Case–control (n = 2) | 0.92 (0.72–1.18) | 0.51 | – | 77.07 | ||
| Risk of bias | Low risk (n = 4) | 0.74 (0.36–1.51) | 0.40 | – | 99.40 | 0.95 |
| Moderate risk (n = 4) | 0.75 (0.54–1.06) | 0.11 | – | 87.65 | ||
| Study population | Asian (n = 1) | 0.38 (0.36–0.39) | < 0.001 | – | – | < 0.001 |
| Western (n = 7) | 0.84 (0.69–1.03) | 0.09 | – | 89.12 | ||
| Incretin-based medicines | ||||||
| All studies (n = 2) | 0.78 (0.61–1.00) | 0.05 | 0.46 | 44.34 | – | |
| Study design | Cohort (n = 2) | 0.78 (0.61–1.00) | 0.05 | – | 44.34 | – |
| Risk of bias | Low risk (n = 1) | 0.70 (0.56–0.87) | < 0.001 | – | – | 0.18 |
| Moderate risk (n = 1) | 0.90 (0.67–1.22) | 0.50 | – | – | ||
| Study population | Asian (n = 1) | 0.70 (0.56–0.87) | < 0.001 | – | – | 0.18 |
| Western (n = 1) | 0.90 (0.67–1.22) | 0.50 | – | – | ||
| Insulin secretagogues | ||||||
| All studies (n = 4) | 1.04 (0.90–1.20) | 0.60 | 0.97 | 9.80 | – | |
| Study design | Cohort (n = 4) | 1.04 (0.90–1.20) | 0.60 | – | 9.80 | – |
| Risk of bias | Low risk (n = 3) | 1.11 (0.96–1.30) | 0.17 | – | < 0.001 | 0.07 |
| Moderate risk (n = 1) | 0.83 (0.63–1.10) | 0.19 | – | – | ||
| Study population | Western (n = 4) | 1.04 (0.90–1.20) | 0.60 | – | 9.80 | – |
| Thiazolidinediones | ||||||
| All studies (n = 6) | 0.87 (0.80–0.95) | < 0.001 | 0.75 | < 0.001 | – | |
| Study design | RCT (n = 1) | 0.52 (0.26–1.04) | 0.07 | – | – | 0.14 |
| Cohort (n = 5) | 0.88 (0.81–0.96) | < 0.001 | – | < 0.001 | ||
| Risk of bias | Low risk (n = 4) | 0.88 (0.80–0.96) | 0.01 | – | < 0.001 | 0.33 |
| Moderate risk (n = 1) | 0.91 (0.68–1.20) | 0.50 | – | – | ||
| High risk (n = 1) | 0.52 (0.26–1.04) | 0.07 | – | – | ||
| Study population | Asian (n = 2) | 0.87 (0.79–0.97) | 0.01 | – | < 0.001 | 0.93 |
| Western (n = 4) | 0.87 (0.73–1.03) | 0.10 | – | < 0.001 | ||
| Insulins | ||||||
| All studies (n = 15) | 0.90 (0.82–0.98) | 0.02 | 0.07 | 72.10 | – | |
| Study design | Cohort (n = 14) | 0.87 (0.79–0.96) | < 0.001 | – | 67.70 | < 0.001 |
| Case–control (n = 1) | 1.15 (1.02–1.29) | 0.03 | – | – | ||
| Risk of bias | Low risk (n = 9) | 0.86 (0.76–0.96) | 0.01 | – | 78.63 | 0.19 |
| Moderate risk (n = 6) | 0.98 (0.83–1.14) | 0.75 | – | 46.38 | ||
| Study population | Asian (n = 3) | 0.79 (0.50–1.25) | 0.31 | – | 41.44 | 0.61 |
| Western (n = 12) | 0.89 (0.80–0.99) | 0.04 | – | 76.47 | ||