title: Carbohydrate quality and quantity and risk of type 2 diabetes in US women.
abstract: BACKGROUND
  Carbohydrate quality may be an important determinant of type 2 diabetes (T2D); however, relations between various carbohydrate quality metrics and T2D risk have not been systematically investigated.
  
  
  OBJECTIVE
  The purpose of this study was to prospectively examine the association between carbohydrates, starch, fibers, and different combinations of these nutrients and risk of T2D in women.
  
  
  METHODS
  We prospectively followed 70,025 women free of cardiovascular disease, cancer, and diabetes at baseline from the Nurses' Health Study (1984-2008). Diet information was collected with the use of a validated questionnaire every 4 y. Cox regression was used to evaluate associations with incident T2D.
  
  
  RESULTS
  During 1,484,213 person-years of follow-up, we ascertained 6934 incident T2D cases. In multivariable analyses, when extreme quintiles were compared, higher carbohydrate intake was not associated with T2D (RR = 0.98; 95% CI: 0.89, 1.08; P-trend = 0.84), whereas starch was associated with a higher risk (RR = 1.23; 95% CI: 1.12, 1.35; P-trend <0.0001). Total fiber (RR = 0.80; 95% CI: 0.72, 0.89; P-trend < 0.0001), cereal fiber (RR = 0.71, 95% CI: 0.65, 0.78; P-trend < 0.0001), and fruit fiber (RR = 0.79; 95% CI: 0.72, 0.85; P-trend < 0.0001) were associated with a lower T2D risk. The ratio of carbohydrate to total fiber intake was marginally associated with a higher risk of T2D (RR = 1.09; 95% CI: 1.00, 1.20; P-trend = 0.04). On the other hand, we found positive associations between the ratios of carbohydrate to cereal fiber (RR = 1.28; 95% CI: 1.17, 1.39; P-trend < 0.0001), starch to total fiber (RR = 1.12; 95% CI: 1.02, 1.23; P-trend = 0.03), and starch to cereal fiber (RR = 1.39; 95% CI: 1.27, 1.53; P-trend < 0.0001) and T2D.
  
  
  CONCLUSIONS
  Diets with high starch, low fiber, and a high starch-to-cereal fiber ratio were associated with a higher risk of T2D. The starch-to-cereal fiber ratio of the diet may be a novel metric for assessing carbohydrate quality in relation to T2D.
authors.affiliation: Departments of Nutrition.
authors.forename: Hala B
authors.identifier: http://orcid.org/0000-0002-6871-3379
authors.initials: HB
authors.lastname: AlEssa
authors.affiliation: Departments of Nutrition.
authors.forename: Shilpa N
authors.identifier: http://orcid.org/0000-0003-0173-9248
authors.initials: SN
authors.lastname: Bhupathiraju
authors.affiliation: Departments of Nutrition.
authors.forename: Vasanti S
authors.initials: VS
authors.lastname: Malik
authors.affiliation: Department of Medicine, University of Massachusetts Medical School, Worcester, MA.
authors.forename: Nicole M
authors.identifier: http://orcid.org/0000-0002-4476-9933
authors.initials: NM
authors.lastname: Wedick
authors.affiliation: Departments of Nutrition.
authors.forename: Hannia
authors.initials: H
authors.lastname: Campos
authors.affiliation: Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA; Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA; and.
authors.forename: Bernard
authors.identifier: http://orcid.org/0000-0001-6907-0056
authors.initials: B
authors.lastname: Rosner
authors.affiliation: Departments of Nutrition, Epidemiology, and Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA; and.
authors.forename: Walter C
authors.identifier: http://orcid.org/0000-0003-1458-7597
authors.initials: WC
authors.lastname: Willett
authors.affiliation: Departments of Nutrition, Epidemiology, and Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA; and Frank.hu@channing.harvard.edu.
authors.forename: Frank B
authors.identifier: http://orcid.org/0000-0002-8412-2261
authors.initials: FB
authors.lastname: Hu
mesh_terms: D000328:Adult; D000465:Algorithms; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control*; D004040:Dietary Carbohydrates / Q000009:adverse effects*; D004043:Dietary Fiber / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D005638:Fruit / Q000737:chemistry*; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009726:Nurses; D018673:Nutrition Policy; D010349:Patient Compliance; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D057566:Self Report; D013213:Starch / Q000009:adverse effects*; D014481:United States / Q000453:epidemiology; D000067348:Whole Grains / Q000737:chemistry*
chemical_list: D004040:Dietary Carbohydrates; D004043:Dietary Fiber; D013213:Starch
keywords: carbohydrate quality; carbohydrate-to-fiber ratio; fiber; starch; type 2 diabetes