title: Caffeinated and caffeine-free beverages and risk of type 2 diabetes.
abstract: BACKGROUND
  Consumption of caffeinated beverages such as coffee and tea has been associated with a lower risk of type 2 diabetes (T2D). Paradoxically, short-term metabolic studies have shown that caffeine impairs postprandial glycemic control.
  
  
  OBJECTIVE
  The objective was to prospectively examine the association of caffeinated compared with caffeine-free beverages, including coffee, tea, sugar-sweetened beverages (SSBs), and carbonated artificially sweetened beverages (ASBs), with T2D risk.
  
  
  METHODS
  We prospectively observed 74,749 women from the Nurses' Health Study (NHS, 1984-2008) and 39,059 men from the Health Professionals Follow-Up Study (HPFS, 1986-2008) who were free of diabetes, cardiovascular diseases, and cancer at baseline.
  
  
  RESULTS
  We documented 7370 incident cases of T2D during 24 y of follow-up in the NHS and 2865 new cases during 22 y of follow-up in the HPFS. After major lifestyle and dietary risk factors were controlled for, caffeinated and caffeine-free SSB intake was significantly associated with a higher risk of T2D in the NHS (RR per serving: 13% for caffeinated SSBs, 11% for caffeine-free SSBs; P < 0.05) and in the HPFS (RR per serving: 16% for caffeinated SSBs, 23% for caffeine-free SSBs; P < 0.01). Only caffeine-free ASB intake in NHS participants was associated with a higher risk of T2D (RR: 6% per serving; P < 0.001). Conversely, the consumption of caffeinated and decaffeinated coffee was associated with a lower risk of T2D [RR per serving: 8% for both caffeinated and decaffeinated coffee in the NHS (P < 0.0001) and 4% for caffeinated and 7% for decaffeinated coffee in the HPFS (P < 0.01)]. Only caffeinated tea was associated with a lower T2D risk among NHS participants (RR per serving: 5%; P < 0.0001).
  
  
  CONCLUSIONS
  Irrespective of the caffeine content, SSB intake was associated with a higher risk of T2D, and coffee intake was associated with a lower risk of T2D.
authors.affiliation: Departments of Nutrition, Harvard School of Public Health, Boston, MA 02115, USA.
authors.forename: Shilpa N
authors.initials: SN
authors.lastname: Bhupathiraju
authors.forename: An
authors.initials: A
authors.lastname: Pan
authors.forename: Vasanti S
authors.initials: VS
authors.lastname: Malik
authors.forename: JoAnn E
authors.initials: JE
authors.lastname: Manson
authors.forename: Walter C
authors.initials: WC
authors.lastname: Willett
authors.forename: Rob M
authors.initials: RM
authors.lastname: van Dam
authors.forename: Frank B
authors.initials: FB
authors.lastname: Hu
mesh_terms: D000328:Adult; D000368:Aged; D001628:Beverages; D015992:Body Mass Index; D002110:Caffeine / Q000008:administration & dosage* / Q000032:analysis; D002253:Carbonated Beverages; D003069:Coffee; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology / Q000503:physiopathology* / Q000517:prevention & control; D004032:Diet; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013549:Sweetening Agents; D013662:Tea
chemical_list: D003069:Coffee; D013549:Sweetening Agents; D013662:Tea; D002110:Caffeine