A prospective study of overall diet quality and risk of type 2 diabetes in women.

OBJECTIVE The aim of this article was to assess the association between the Alternate Healthy Eating Index (AHEI) and risk of type 2 diabetes in women. RESEARCH DESIGN AND METHODS A total of 80,029 women aged 38-63 years in the Nurses' Health Study were followed from 1984 to 2002. The AHEI score was computed from dietary information collected from five repeated food frequency questionnaires administered between 1984 and 1998. Relative risks (RRs) for type 2 diabetes were calculated using Cox proportional hazards models and adjusted for known diabetes risk factors. We also examined how changes in score in 4, 6-8, and 10-12 years are associated with diabetes risk. RESULTS We ascertained 5,183 incident cases of type 2 diabetes during 18 years of follow-up. Women who scored high on the AHEI had a lower risk (RR comparing top to bottom score quintile 0.64 [95% CI 0.58-0.71], P(trend) < 0.0001) for diabetes. Women with consistently high AHEI scores throughout follow-up, compared with those with consistently low scores, had the lowest risk for diabetes. In addition, women whose AHEI scores improved during follow-up, even during recent years, had a lower risk of diabetes than did women whose (low) score did not change. CONCLUSIONS A higher AHEI score is associated with a lower risk of type 2 diabetes in women. Therefore, the AHEI score may be a useful clinical tool to assess diet quality and to recommend for the prevention of diabetes.