Red Blood Cell Fatty Acids and Incident Diabetes Mellitus in the Women's Health Initiative Memory Study

Abstract

ContextThe relations between dietary and/or circulating levels of fatty acids and the development of type 2 diabetes is unclear. Protective associations with the marine omega‐3 fatty acids and linoleic acid, and with a marker of fatty acid desaturase activity delta‐5 desaturase (D5D ratio) have been reported, as have adverse relations with saturated fatty acids and D6D ratio.ObjectiveTo determine the associations between red blood cell (RBC) fatty acid distributions and incident type 2 diabetes.DesignProspective observational cohort study nested in the Women's Health Initiative Memory Study.SettingGeneral populationSubjectsPostmenopausal womenMain outcome measuresincident type 2 diabetesResultsThere were 703 new cases of type 2 diabetes over 11 years of follow up among 6379 postmenopausal women. In the fully adjusted models, baseline RBC D5D ratio was inversely associated with incident type 2 diabetes [Hazard Ratio (HR) 0.88, 95% confidence interval (CI) 0.81–0.95) per 1 SD increase. Similarly, baseline RBC D6D ratio and palmitic acid were directly associated with incident type 2 diabetes (HR 1.14, 95% CI 1.04–1.25; and HR 1.24, 95% CI 1.14–1.35, respectively). Cumulative Nelson‐Aalen hazard estimates of incident diabetes by baseline D5D ratio, D6D ratio and palmitic acid level are shown in the Figure. None of these relations were materially altered by excluding incident cases in the first two years of follow‐up or by excluding women with glucose >125 mg/dL at baseline. There were no significant relations with eicosapentaenoic, docosahexaenoic or linoleic acids.ConclusionsOur findings confirm those of past researchers showing that altered blood fatty acid desaturase activities and/or palmitic acid levels are significantly associated with future risk for diabetes. Whether these fatty acid abnormalities are causally related to the development of type 2 diabetes cannot be determined from this study, but our findings suggest that measuring RBC fatty acid distributions may help to identify subjects at increased risk for type 2 diabetes.Support or Funding InformationThis study was supported in part under a contract with the NHLBI (BAA 19).