Table 1.
General characteristics of the reviewed studies
| Characteristic | All (N = 155) | Cohort studies (N = 100) | Case-control studies (N = 55) |
|---|---|---|---|
| N (%) | N (%) | N (%) | |
| Publication year | |||
| 2000–2008 | 11 (7%) | 4 (4%) | 7 (13%) |
| 2009 | 10 (6%) | 5 (5%) | 5 (9%) |
| 2010 | 11 (7%) | 5 (5%) | 6 (11%) |
| 2011 | 18 (12%) | 12 (12%) | 6 (11%) |
| 2012 | 34 (22%) | 27 (27%) | 7 (13%) |
| 2013 | 33 (21%) | 18 (18%) | 15 (27%) |
| 2014 | 26 (17%) | 21 (21%) | 5 (9%) |
| 2015 | 12 (8%) | 8 (8%) | 4 (7%) |
| Geographic region of study population | |||
| North America | 36 (23%) | 21 (21%) | 15 (27%) |
| Europe | 65 (42%) | 38 (38%) | 27 (49%) |
| Southeast Asia | 51 (33%) | 39 (39%) | 12 (22%) |
| Middle east | 1 (1%) | 1 (1%) | 0 (0%) |
| Multiple regions | 2 (1%) | 1 (1%) | 1 (2%) |
| Data source | |||
| Administrative insurance claims | 47 (30%) | 38 (38%) | 9 (16%) |
| Medical records | 44 (28%) | 21 (21%) | 23 (42%) |
| Disease registry | 6 (4%) | 5 (5%) | 1 (2%) |
| Longitudinal survey/Secondary data analysis† | 8 (5%) | 7 (7%) | 1 (2%) |
| Primary data collection‡ | 10 (6%) | 0 (0%) | 10 (18%) |
| Multiple linked data sources | 40 (26%) | 29 (29%) | 11 (20%) |
| Exposure§ | |||
| Alpha-glucosidase inhibitors | 12 (8%) | 8 (8%) | 4 (7%) |
| Dipeptidyl peptidase-4 inhibitors | 2 (1%) | 1 (1%) | 1 (2%) |
| Injectable glucagon-like peptide-1 receptor agonists | 2 (1%) | 1 (1%) | 1 (2%) |
| Insulin | 80 (52%) | 49 (49%) | 31 (56%) |
| Meglitinides | 8 (5%) | 4 (4%) | 4 (7%) |
| Metformin | 77 (50%) | 41 (41%) | 36 (65%) |
| Sulfonylureas | 48 (31%) | 25 (25%) | 23 (42%) |
| Thiazolidinediones | 55 (35%) | 34 (34%) | 21 (38%) |
| Any glucose-lowering medication | 11 (7%) | 8 (8%) | 3 (5%) |
| Any agent from a pre-specified group of therapeutic classes | 8 (5%) | 6 (6%) | 2 (4%) |
| Polytherapy with multiple therapeutic agents | 11 (7%) | 8 (8%) | 3 (5%) |
| Outcomes§ | |||
| Lip, oral cavity and pharynx cancer | 3 (2%) | 3 (3%) | 0 (0%) |
| Digestive organs cancer | 60 (39%) | 31 (31%) | 29 (53%) |
| Respiratory and intrathoracic organs cancer | 15 (10%) | 11 (11%) | 4 (7%) |
| Skin cancer | 4 (3%) | 4 (4%) | 0 (0%) |
| Breast cancer | 27 (17%) | 22 (22%) | 5 (9%) |
| Female genital organs cancer | 10 (6%) | 8 (8%) | 2 (4%) |
| Male genital organs cancer | 26 (17%) | 19 (19%) | 7 (13%) |
| Urinary tract cancer | 28 (18%) | 22 (22%) | 6 (11%) |
| Eye, brain and other parts of central nervous system cancer | 1 (1%) | 0 (0%) | 1 (2%) |
| Thyroid and other endocrine glands cancer | 3 (2%) | 3 (3%) | 0 (0%) |
| Lymphoid, hematopoietic and related tissue cancer | 4 (3%) | 4 (4%) | 0 (0%) |
| Any cancer¶ | 49 (32%) | 42 (42%) | 7 (13%) |
| Any cancer from a pre-specified group of cancer types | 2 (1%) | 2 (2%) | 0 (0%) |
†
Secondary data analyses: analyses of data collected from clinical trials, prospective cohort studies or case-control studies conducted for a different research question
‡
Primary data collection: prospective cohort studies, case-control studies with recruitment, interview, questionnaire or follow-up
§
Categories are not mutually exclusive
¶
Including studies that evaluated any cancer except nonmelanoma skin cancer (NMSC) (7 cohort and 0 case-control studies)