Hermann 2001.
| Methods |
Parallel randomised controlled clinical trial Randomisation ratio: 1:1 Superiority design |
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| Participants |
Inclusion criteria: people with type 2 diabetes with insulin therapy > 1 year. BMI > 27 kg/m2 for men and > 25 kg/m2 for women. HbA1c value higher than the upper reference limit + 2%. Insulin dose 0.4‐1.0 U/kg/day. C‐peptide after 1 mg glucagon intravenously > 0.6 nmol/L Exclusion criteria: treatment with oral antidiabetic agents within the last 6 months. Presence of any of the usual contraindications for metformin. Abnormal serum creatinine concentration. Transaminases > 2 x the upper reference limit. Overconsumption of alcohol Diagnostic criteria: not stated |
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| Interventions |
Number of study centres: 3 Treatment before study: insulin: intervention 0.75 ± 0.28 U/kg/day and control 0.73 ± 0.23 U/kg/day Titration period: 2 weeks |
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| Outcomes |
Primary outcome(s) (as stated in the publication): glycaemic control (HbA1c, FBG), bodyweight and BMI, insulin dose, lipids Secondary outcomes (as stated in the publication): waist‐hip ratio, blood pressure, fibrinogen, C‐peptide, serum B12, compliance |
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| Study details |
Total study duration: 15 months Run‐in period: 12 weeks Study terminated early (for benefit/because of adverse events): no |
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| Publication details |
Language of publication: English Funding source: none Publication status: peer‐reviewed journal |
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| Stated aim of study | Quote from publication: "To assess the adjunct effect of metformin to insulin in type 2 diabetes." | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Quote from publication: "...the patients entered a 12‐month double‐blind treatment phase randomly allocated to metformin or placebo in parallel groups and as adjunct to their current insulin therapy" |
| Allocation concealment (selection bias) | Low risk | Quote from publication: "Randomization was performed by center in block of four." |
| Blinding of participants and personnel (performance bias) Adverse events | Low risk |
Quote from publication: "The study was a 12‐month double‐blind placebo‐controlled trial..." Comment: probably the participants and personnel were blinded |
| Blinding of participants and personnel (performance bias) HbA1c, FPG, lipids | Low risk |
Quote from publication: "The study was a 12‐month double‐blind placebo‐controlled trial..." Comment: probably the participants and personnel were blinded |
| Blinding of participants and personnel (performance bias) Insulin dose | Low risk |
Quote from publication: "The study was a 12‐month double‐blind placebo‐controlled trial..." Comment: probably the participants and 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 |
| Blinding of outcome assessment (detection bias) Insulin dose | Unclear risk | Comment: unclear if the outcome assessor was blinded |
| Incomplete outcome data (attrition bias) Adverse events | Low risk | Comment: data on adverse events were reported |
| Incomplete outcome data (attrition bias) HbA1c, FPG, lipids | Low risk | Comment: outcome data were collected and reported |
| Incomplete outcome data (attrition bias) Insulin dose | Low risk | Comment: data on insulin dose were collected and reported |
| Selective reporting (reporting bias) | Unclear risk | Comment: data were reported graphically, unclear |
| Other bias | Unclear risk | Comment: medication was funded by a pharmaceutical company |