Oslo 1987.
| Methods |
Parallel randomised controlled clinical trial Randomisation ratio:1:1:1 Superiority design |
|
| Participants |
Inclusion criteria: age: 18‐45 years, diabetes duration > 7 years, but < 30 years, diabetes diagnosis before age = 30, negative for C‐peptide Exclusion criteria: clinical signs of nephropathy (serum creatinine ≤ 150 µmol/L), systemic hypertension (diastolic blood pressure ≤ 100 mm Hg), history of neuropathy, proliferative retinopathy, pregnant, medication other than insulin (apart from contraceptives) Diagnostic criteria: C‐peptide negative insulin dependent diabetes |
|
| Interventions |
Number of study centres: 1 Treatment before study: two daily insulin injections of mixed insulin |
|
| Outcomes | Outcomes reported in abstract of publication: HbA1c, hypoglycaemic coma, ketoacidosis, cutaneous infections at injection site, insulin antibodies, retinopathy, urinary albumin excretion, glomerular hyperfiltration, sensory and motor nerve conduction velocity | |
| Study details |
Run‐in period: 2 months Study terminated before regular end: no |
|
| Publication details |
Language of publication: English Funding: partially commercial Publication status: peer‐reviewed journal/full article |
|
| Stated aim of study | Quote from publication: "To study the influence of long‐term near‐normoglycaemia on early stages of microangiopathy and neuropathy in young insulin dependent diabetic patients" | |
| Notes | For several outcomes results have only be reported after 2 years | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Quote from publication: "To ensure comparable treatment groups a block randomizations procedure was chosen. The patients were randomised into three groups by a computer programme making the best possible distribution of basic characteristics in the following priority: Age, duration of disease, sex, initial HbA1c value and retinopathy grading" Comment: considered adequate |
| Allocation concealment (selection bias) | Unclear risk | Comment: not described |
| Blinding of participants and personnel (performance bias) Objective Outcomes | Low risk | Comment: not blinded, but risk of bias considered low for objective outcomes |
| Blinding of participants and personnel (performance bias) Subjective Outcomes | High risk | Comment: not blinded |
| Blinding of outcome assessment (detection bias) Objective Outcomes | Low risk | Quote from publication: "To avoid observer bias, all pictures were coded and evaluated in a masked manner by the ophthalmologist" Comment: blinded outcome assessment of retinopathy, unclear for other outcomes |
| Blinding of outcome assessment (detection bias) Subjective Outcomes | Unclear risk | Comment: not described |
| Incomplete outcome data (attrition bias) All outcomes | High risk | Quote from publication: "Data collected until change of treatment was used for statistical analysis" Comment: About 35% of the patients in the control group and 15% of patients in the treatment groups changed the treatment arm at some point during the study; it is not clear across the different publications of the Oslo study how these data were handled. Since the proportion of patients changing treatment was substantial, risk of bias was considered high |
| Selective reporting (reporting bias) | Unclear risk | Comment: data were analysed for many different times of follow‐up |
| Other bias | Unclear risk | Comment: reporting insufficient to assess the risk of other biases |