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. 2016 Sep 18;2016(9):CD006992. doi: 10.1002/14651858.CD006992.pub2

Longnecker 1986.

Methods Cross‐over randomised controlled clinical trial
Randomisation ratio: 1:1
Superiority design
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
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
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
Publication details Language of publication: English
Funding source: Public Health Service Grant, ADA, Upjohn
Publication status: peer‐reviewed journal
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