AbstractObjectiveTo investigate the association between macronutrient intake and type 2 diabetes risk in middle-aged Australian women.DesignA prospective cohort study, with 6 years (2002–2007) of follow up. Dietary intake was assessed with a validated FFQ. Relative risks with 95 % confidence intervals were used to examine risk associations.SettingAustralian Longitudinal Study on Women's Health, Australia.SubjectsAustralian women (n 8370) from the Australian Longitudinal Study on Women's Health aged 45–50 years and free of type 2 diabetes at baseline.ResultsAfter 6 years of follow-up, 311 women developed type 2 diabetes. After adjusting for sociodemographic, lifestyle and other dietary risk factors, MUFA, total n-3 PUFA, α-linolenic acid and total n-6 PUFA intakes were positively associated with the incidence of type 2 diabetes. The relative risks for type 2 diabetes for the highest compared with the lowest quintiles were 1·64 (95 % CI 1·06, 2·54), P = 0·04 for MUFA; 1·55 (95 % CI 1·03, 2·32), P = 0·01 for n-3 PUFA; 1·84 (95 % CI 1·25, 2·71), P < 0·01 for α-linolenic acid; and 1·60 (95 % CI 1·03, 2·48), P = 0·04 for n-6 PUFA. Other dietary macronutrients were not significantly associated with diabetes risk.ConclusionsThe data indicate that consumption of MUFA, n-3 PUFA and n-6 PUFA may influence the risk of developing type 2 diabetes in women.