Meta-analysis of the effects of n-3 polyunsaturated fatty acids on haematological and thrombogenic factors in type 2 diabetes

Randomised controlled trials (cross-over and parallel) in adults with type 2 diabetes; both sexes; 12 trials, 847 participants; mean duration 8.5 weeks; all included both genders; two trials excluded pre-menopausal women.

Oral marine-derived n-3 PUFA (EPA/DHA) supplementation; daily dose ranged 0.9–10 g (mean 4.3 g/day; median 3 g/day); mean duration 8.5 weeks; forms included fish oil, cod-liver oil, or purified EPA/DHA.

n-3 PUFA supplementation reduced diastolic blood pressure by 1.8 mmHg (95% CI 0.0 to 3.6; p=0.05) across five trials (n=248) and increased factor VII by 24.9% (95% CI 7.2 to 42.6; p=0.006) across two trials (n=116). No significant effects on systolic blood pressure, fibrinogen, or heart rate. Conclusion: supplementation may modestly lower diastolic blood pressure and may increase factor VII; overall cardiovascular risk impact remains uncertain; larger, longer, higher-quality trials are needed to define the role of n-3 PUFA in cardiovascular risk markers and outcomes in type 2 diabetes.

Small median trial size; short mean duration; heterogeneity and measurement variability; not all outcomes were pooled; potential publication bias indicated by funnel plots; incomplete reporting of randomisation/blinding; no individual patient data.