GLAMT 1993

Methods	Gamma linolenic acid multicentre trial (GLAMT) RCT, 2‐arm, parallel (n‐6 GLA vs non‐fat), 1 year Summary risk of bias: moderate to high
Participants	People with mild diabetic neuropathy CVD risk: moderate Control: randomised 57, analysed 48 (with at least one evaluation) Intervention: randomised 54, analysed 52 Mean years in trial: control 1.0, randomised 1.0 % male: control 79%, intervention 67% Mean age (SD) in years: control 52.9 (11.4), intervention 53.3 (11.1) Age range: unclear Smokers: unclear Hypertension: unclear Medications taken by at least 50% of those in the control group: insulin Medications taken by 20%‐49% of those in the control group: not reported Medications taken by some, but less than 20% of the control group: not reported Location: UK and Finland Ethnicity: not reported
Interventions	Type: supplement Comparison: GLA (n‐6) vs placebo (paraffin) Control aims: 12 capsules/d paraffin Intervention aims: 12 capsules/d evening primrose oil (EP4, equivalent to Epogam): 0.48 g/d GLA plus LA (stated as the major constituent, dose not given, if assume 0.7 g/capsule then 8.4 g/d*) Dose aim: increase 0.48 g/d GLA or 4 kcal or 0.2% E GLA, increase ˜8.4 g/d LA or 76 kcal or 3.8% E LA, total 4% E n‐6 Baseline n‐6: unclear Compliance by biomarkers: unclear, no serum total cholesterol or tissue fatty acid levels reported Compliance by dietary intake: unclear Energy intake: not reported Total fat intake: not reported Saturated fat intake: not reported PUFA intake: not reported PUFA n‐3 intake: not reported PUFA n‐6 intake: not reported Trans fat intake: not reported MUFA intake: not reported CHO intake: not reported Sugars intake: not reported Protein intake: not reported Alcohol intake: not reported Duration of intervention: 1 year
Outcomes	Main study outcome: measures of diabetic neuropathy Dropouts: control 17, intervention 10 Available outcomes: MI, cancer (no deaths)
Notes	Study funding: Scotia Pharmaceuticals *EPO described as being ˜70% LA in some publications, this and a 1‐g capsule size have been assumed where no other details are provided Response to contact: no response to our attempted contact
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Described as double‐blind, and "[a]ctive and placebo capsules were indistinguishable in taste or appearance"
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Unclear, though study described as double‐blind no methods or statement of blinding of outcome assessors was mentioned
Incomplete outcome data (attrition bias) All outcomes	High risk	Reasons for withdrawal usually given, but high and dissimilar
Selective reporting (reporting bias)	Unclear risk	No clear protocol or trials registry entry found
Attention Bias	Low risk	Capsule only intervention and provided to all, other follow ups appeared consistent for all
Compliance	Unclear risk	Not reported
Other bias	Low risk	None identified