GLAMT 1993.

Methods	Gamma Linolenic Acid Multicentre Trial (GLAMT) RCT, 2‐arm, parallel (n6 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 ≥ 1 evaluation) Intervention: randomised 54, analysed 52 Mean years in trial: control 1.0, randomised 1.0 % male: intervention 67%, control 79%, Age, mean (SD) years: intervention 53.3 (11.1), control 52.9 (11.4) Age range: unclear Smokers: unclear Hypertension: unclear Medications taken by ≥ 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 < 20% of the control group: not reported Location: UK and Finland Ethenicty: 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 n6 Baseline PUFA: unclear Compliance by biomarkers: unclear, no serum TC or tissue fatty acid levels reported Compliance by dietary intake: unclear Energy intake: not reported Total fat intake: not reported SFA 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 Compliance, other methods: not reported Inclusion basis: aimed to increase GLA intake rather than total PUFA. Dose aim appeared to be ˜4% E PUFA (from omega‐6 data), >10% more than assumed baseline of 6% E PUFA. No confirmatory biomarker or intake data PUFA dose: 4% E PUFA (estimated from aim) Duration of intervention: 1 year
Outcomes	Main trial outcome: measures of diabetic neuropathy Dropouts: intervention 10, control 17 Available outcomes: MI, cancer (no deaths) Response to contact: contact attempted but no response to date.
Notes	Trial funding: Scotia Pharmaceuticals
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 Quote: "Active and placebo capsules were indistinguishable in taste or appearance"
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Unclear, though trial 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	Appeared similar
Compliance	Unclear risk	Neither tissue PUFA biomarkers nor TC data reported
Other bias	Low risk	None identified