Associations of dietary flavonoids with risk of type 2 diabetes, and markers of insulin resistance and systemic inflammation in women: A prospective study and cross-sectional analysis

Objective: Flavonoids, as antioxidants. may prevent the progressive impairment of pancreatic beta-cell function due to oxidative stress and may thus reduce the occurrence of type 2 diabetes, The aim of the present study was to examine the association of dietary flavonol and flavone intake with type 2 diabetes, and biomarkers of insulin resistance and systemic inflammation, Methods: In 38,018 women aged >= 45 y and free of cardiovascular disease. cancer and diabetes with an average 8.8y of follow-up. we calculated relative risks (RRs) of incident type 2 diabetes (1,614 events) according to dietary intake of total or individual flavonols and flavones and flavonoid-rich foods. We also measured and examined plasma concentrations of insulin, HbA(1C) CRP. and IL-6 in relation to total flavonol and flavone intake among 344 nondiabetic women. Results: During 332,905 person-years of follow-up, none of total flavonols and flavones, quercetin. kaempferol, myricetin, apigenin, and luteolin was significantly associated with risk of type 2 diabetes, Among flavonoid-rich foods, apple and tea consumption was associated with diabetes risk, Women consuming, I apple/d showed a significant 28% reduced risk of type 2 diabetes compared with those who consumed no apples (the multivariate-adjusted RR = 0.72, 95% Cl: 0.56. 0.92 p = 0.006 for trend), Tea consumption was also inversely associated with diabetes risk but with a borderline significant trend 4 cups/d vs, none RR 0.73. 95% Cl: 0.52-1.01 p for trend = 0.06). In 344 nondiabetic women. total intake of flavonols and flavones v, as not significantly related to plasma concentrations of fasting insulin, HbA(1C) CRP, or IL-6. Conclusions: These results do not support the hypothesis that high intake of flavonols and flavones reduces the development of type 2 diabetes. although we cannot rule out a modest inverse association with intake of apples and tea.