Longnecker 1986.
| Methods | 
Cross‐over randomised controlled clinical trial Randomisation ratio: 1:1 Superiority design  | 
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| Participants | 
Inclusion criteria: severely hyperglycaemic patients with type 2 diabetes with insulin monotherapy failed to sulphonylurea therapy Controls were nondiabetic women comparable with patients in age and weight. Exclusion criteria: not stated Diagnostic criteria: not stated  | 
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| Interventions | 
Number of study centres: 1 Treatment before study: insulin 64 ± 5.6 U/day (insulin regimen: once or twice daily, regular and/or isophane insulin) Titration period: 1 week  | 
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| Outcomes | Primary outcome(s) (as stated in the publication): glycaemic control (HbA1c, fasting blood glucose), plasma glucose and C‐peptide before and after standardised meal, weight, C‐peptide, drug compliance, side effects | |
| Study details | 
Total study duration: 20 weeks Run‐in period: 1 week Study terminated early (for benefit/because of adverse events): no  | 
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| Publication details | 
Language of publication: English Funding source: Public Health Service Grant, ADA, Upjohn Publication status: peer‐reviewed journal  | 
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| Stated aim of study | Quote from publication: "To evaluate the efficacy of adding tolazamide, an oral agent, to insulin in a group of severely hyperglycaemic patients with NIDDM, all of whom had previously failed to respond to therapy with oral sulfonylurea agent alone." | |
| Notes | Carry‐over effect not described | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement | 
| Random sequence generation (selection bias) | Unclear risk | Comment: not possible to judge whether the sequence generation was adequate | 
| Allocation concealment (selection bias) | Unclear risk | Comment: not possible to judge whether the allocation to the intervention and control group was concealed | 
| Blinding of participants and personnel (performance bias) Adverse events | Unclear risk | 
Quote from publication: (from the abstract) "Using a double‐blind crossover design, ..." Comment: probably the participants and the personnel were blinded  | 
| Blinding of participants and personnel (performance bias) HbA1c, FPG, lipids | Unclear risk | 
Quote from publication: (from the abstract) "Using a double‐blind crossover design, ..." Comment: probably the participants and the personnel were blinded  | 
| Blinding of outcome assessment (detection bias) Adverse events | Unclear risk | Comment: unclear if the outcome assessor was blinded | 
| Blinding of outcome assessment (detection bias) HbA1c, FPG, lipids | Unclear risk | Comment: unclear if the outcome assessor was blinded | 
| Incomplete outcome data (attrition bias) Adverse events | High risk | Comment: the effects on weight and side effects were not reported | 
| Incomplete outcome data (attrition bias) HbA1c, FPG, lipids | Low risk | Comment: outcome date were collected and reported | 
| Selective reporting (reporting bias) | High risk | Comment: the effects on weight and side effects were not reported | 
| Other bias | Unclear risk | Comment: only 12 participants were included |