Table 2 Meta-analysis results.
Variables | No. of studies | Pooled Relative Risk | Model of meta-analysis | Heterogeneity test | ||
|---|---|---|---|---|---|---|
RR (95% CI) | P Z | I 2 (%) | P H | |||
Overall | 72 | 1.01 (0.91–1.12) | 0.89 | Fixed | 0.0 | 0.93 |
Type of DPP-4 inhibitors | ||||||
 Sitagliptin | 38 | 1.03 (0.88–1.21) | 0.68 | Fixed | 0.0 | 0.79 |
 Saxagliptin | 13 | 0.96 (0.81–1.13) | 0.63 | Fixed | 0.0 | 0.81 |
 Alogliptin | 10 | 1.53 (0.93–2.53) | 0.10 | Fixed | 0.0 | 0.68 |
 Linagliptin | 11 | 0.84 (0.55–1.28) | 0.41 | Fixed | 0.0 | 0.70 |
Type of cancers | ||||||
Reproductive system | 80 | 0.87 (0.73–1.05) | 0.15 | Fixed | 0.0 | 1.00 |
 Cervix carcinoma | 8 | 1.38 (0.54–3.50) | 0.50 | Fixed | 0.0 | 0.75 |
 Prostate cancer | 22 | 0.89 (0.69–1.14) | 0.37 | Fixed | 0.0 | 0.97 |
 Breast cancer | 25 | 0.72 (0.50–1.06) | 0.09 | Fixed | 0.0 | 0.98 |
 Ovarian cancer | 8 | 1.06 (0.48–2.35) | 0.89 | Fixed | 0.0 | 0.87 |
 Endometrial cancer | 6 | 0.53 (0.22–1.28) | 0.16 | Fixed | 0.0 | 0.70 |
 Uterine cancer | 9 | 1.77 (0.77–4.04) | 0.18 | Fixed | 0.0 | 0.85 |
 Vulval cancer | 1 | 0.33 (0.01–8.16) | 0.50 | Fixed | — | — |
 Testis cancer | 1 | 0.33 (0.01–8.11) | 0.50 | Fixed | — | — |
 Digestive system | 89 | 0.93 (0.77–1.13) | 0.46 | Fixed | 0.0 | 1.00 |
 Colon cancer | 27 | 0.96 (0.71–1.31) | 0.81 | Fixed | 0.0 | 0.98 |
 Pancreatic cancer | 16 | 0.83 (0.51–1.35) | 0.46 | Fixed | 0.0 | 0.93 |
 Gastric cancer | 8 | 1.35 (0.76–2.40) | 0.30 | Fixed | 0.0 | 0.92 |
 Salivary gland neoplasm | 3 | 1.40 (0.28–7.10) | 0.68 | Fixed | 0.0 | 0.55 |
 Rectal cancer | 6 | 0.41 (0.18–0.95) | 0.04 | Fixed | 0.0 | 0.53 |
 Gallbladder cancer | 2 | 1.00 (0.14–7.06) | 1.00 | Fixed | 0.0 | 0.34 |
 Hepatic cancer | 8 | 1.02 (0.54–1.91) | 0.96 | Fixed | 0.0 | 0.85 |
 Bile duct cancer | 4 | 0.77 (0.28–2.12) | 0.61 | Fixed | 0.0 | 0.60 |
 Laryngeal cancer | 6 | 0.71 (0.28–1.81) | 0.47 | Fixed | 0.0 | 0.58 |
 Anal cancer | 1 | 0.20 (0.01–4.17) | 0.30 | Fixed | — | — |
 Lip carcinoma | 3 | 4.33 (0.74–25.54) | 0.11 | Fixed | 0.0 | 0.90 |
 Oesophageal cancer | 3 | 0.75 (0.17–3.33) | 0.70 | Fixed | 0.0 | 0.58 |
 Tongue cancer | 1 | 0.32 (0.01–7.68) | 0.48 | Fixed | — | — |
 Cholangioma | 1 | 2.95 (0.12–71.86) | 0.51 | Fixed | — | — |
 Integumentary system | 30 | 1.12 (0.75–1.67) | 0.58 | Fixed | 0.0 | 1.00 |
 Malignant melanoma | 12 | 0.87 (0.48–1.59) | 0.66 | Fixed | 0.0 | 0.90 |
 Basal cell carcinoma | 11 | 0.95 (0.42–2.12) | 0.90 | Fixed | 0.0 | 0.60 |
 Skin cancer | 7 | 1.79 (0.86–3.71) | 0.12 | Fixed | 0.0 | 1.00 |
 Urinary system | 32 | 1.22 (0.92–1.61) | 0.16 | Fixed | 0.0 | 0.98 |
 Renal cancer | 17 | 1.38 (0.89–2.13) | 0.15 | Fixed | 0.0 | 0.96 |
 Bladder cancer | 15 | 1.12 (0.77–1.61) | 0.56 | Fixed | 0.0 | 0.80 |
 Hematologic system | 13 | 1.05 (0.65–1.68) | 0.85 | Fixed | 0.0 | 0.92 |
 Leukemia | 4 | 0.93 (0.45–1.93) | 0.85 | Fixed | 0.0 | 0.74 |
 Lymphoma | 8 | 1.29 (0.67–2.49) | 0.45 | Fixed | 0.0 | 0.88 |
 Hodgkin’s disease | 1 | 0.20 (0.01–4.13) | 0.30 | Fixed | — | — |
 Respiratory system | 23 | 1.08 (0.82–1.41) | 0.61 | Fixed | 0.0 | 0.91 |
 Lung cancer | 19 | 1.00 (0.76–1.33) | 0.98 | Fixed | 0.0 | 0.95 |
 Bronchial carcinoma | 4 | 2.55 (0.86–7.59) | 0.09 | Fixed | 0.0 | 0.55 |
 Motor system | 5 | 1.68 (0.57–5.01) | 0.35 | Fixed | 0.0 | 0.64 |
 Bone cancer | 5 | 1.68 (0.57–5.01) | 0.35 | Fixed | 0.0 | 0.64 |
 Endocrine system | 17 | 0.78 (0.43–1.41) | 0.41 | Fixed | 0.0 | 0.91 |
 Thyroid cancer | 14 | 0.73 (0.38–1.40) | 0.35 | Fixed | 0.0 | 0.91 |
 Thymoma | 2 | 2.98 (0.31–28.48) | 0.34 | Fixed | 0.0 | 0.91 |
 Pituitary tumor | 1 | 0.17 (0.01–4.05) | 0.27 | Fixed | — | — |
 Nervous system | 2 | 3.01 (0.31–28.84) | 0.34 | Fixed | 0.0 | 0.99 |
 Brain cancer | 2 | 3.01 (0.31–28.84) | 0.34 | Fixed | 0.0 | 0.99 |
 Cardiovascular system | 2 | 0.99 (0.14–7.04) | 0.99 | Fixed | 0.0 | 0.34 |
 Vascular neoplasm | 1 | 2.98 (0.12–73.03) | 0.50 | Fixed | — | — |
 Haemangioma | 1 | 0.33 (0.01–8.11) | 0.50 | Fixed | — | — |
Type of comparators | ||||||
 Placebo | 30 | 0.98 (0.87–1.11) | 0.79 | Fixed | 0.0 | 0.89 |
 Sulfonylureas | 14 | 1.40 (0.99–1.96) | 0.05 | Fixed | 13.6 | 0.31 |
 Thiazolidinediones | 7 | 0.60 (0.27–1.33) | 0.21 | Fixed | 11.6 | 0.34 |
 Metformin | 10 | 1.14 (0.57–2.28) | 0.72 | Fixed | 0.0 | 1.00 |
 SGLT inhibitors | 1 | 0.33 (0.04–3.18) | 0.34 | Fixed | — | — |
 GLP-1 RAs | 5 | 0.85 (0.39–1.83) | 0.68 | Fixed | 6.3 | 0.37 |
 Other antidiabetic agents | 5 | 0.88 (0.32–2.42) | 0.80 | Fixed | 0.0 | 0.77 |
Trial duration | ||||||
 Less than 52 weeks | 44 | 1.32 (0.93–1.89) | 0.12 | Fixed | 0.0 | 0.98 |
 52 weeks or more | 28 | 0.98 (0.88–1.10) | 0.73 | Fixed | 0.0 | 0.49 |
Mean age | Â | Â | Â | Â | Â | Â |
 Less than 60 years | 54 | 1.10 (0.85–1.40) | 0.49 | Fixed | 0.0 | 0.97 |
 60 years or more | 16 | 0.99 (0.88–1.12) | 0.89 | Fixed | 17.8 | 0.25 |
Mean HbA1c | ||||||
 Less than 8% | 21 | 1.06 (0.91–1.24) | 0.43 | Fixed | 0.0 | 0.49 |
 8% or more | 44 | 0.94 (0.81–1.10) | 0.45 | Fixed | 0.0 | 0.95 |
Mean BMI | ||||||
 Less than 30 kg/m2 | 25 | 1.28 (0.88–1.86) | 0.20 | Fixed | 0.0 | 0.80 |
 30 kg/m2 or more | 37 | 0.97 (0.86–1.10) | 0.58 | Fixed | 0.0 | 0.87 |
Mean diabetes duration | ||||||
 Less than 8 years | 37 | 1.23 (0.96–1.58) | 0.10 | Fixed | 0.0 | 0.80 |
 8 years or more | 14 | 0.97 (0.86–1.10) | 0.61 | Fixed | 0.0 | 0.66 |
