Plasma omega-3 fatty acids and incident diabetes in older adults

Although long-chain omega-3 fatty acid (n-3 FA) consumption estimated via food-frequency questionnaires has been associated with a higher incidence of diabetes, limited prospective data on diabetes risk are available that use objective biomarkers of n – 3 FAs. We sought to examine the relation between plasma phospholipid n – 3 FAs and incident diabetes. We prospectively analyzed data in 3088 older men and women (mean age: 75 y) from the Cardiovascular Health Study (1992 to 2007). Plasma phospholipid n – 3 FAs were measured by using gas chromatography, and incident diabetes was ascertained by using information on hypoglycemic agents and serum glucose. We used Cox proportional hazards models to estimate multivariable-adjusted relative risks. During a median follow-up of 10.6 y, 204 new cases of diabetes occurred. In a multivariable model that controlled for age, sex, race, clinic site, body mass index, alcohol intake, smoking, physical activity, LDL cholesterol, and linoleic acid, relative risks (95% CIs) for diabetes were 1.0 (reference), 0.96 (0.65, 1.43), 1.03 (0.69, 1.54), and 0.64 (0.41, 1.01) across consecutive quartiles of phospholipid eicosapentaenoic acid and docosahexaenoic acid (P for trend = 0.05). Corresponding relative risks (95% CIs) for phospholipid alpha-linolenic acid (ALA) were 1.0 (reference), 0.93 (0.65,
1.34), 0.99 (0.68, 1.44), and 0.57 (0.36, 0.90) (P for trend = 0.03). With the use of objective biomarkers, long-chain n-3 FAs and ALA were not associated with a higher incidence of diabetes. Individuals with the highest concentrations of both types of FAs had lower risk of diabetes. [Authors abstract]
There is controversy regarding the effects of long chain n-3 fatty acids (FAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and plant derived alpha-linolenic acid (ALA) on the risk of diabetes. The measurement of circulating fatty acids used in this study provides an objective measure of dietary exposure to various nutrients and also allows for the assessment of individual n-3 FAs such as ALA, EPA, and DHA.  Higher concentrations of plasma phospholipid ALA and EPA+DHA were associated with lower risk of diabetes in older adults. [Editors comments]