title: Coffee and caffeine intake and incidence of type 2 diabetes mellitus: a meta-analysis of prospective studies.
abstract: OBJECTIVE
  Coffee and caffeine have been linked to type 2 diabetes mellitus (T2DM). A dose-response meta-analysis of prospective studies was conducted to assess the association between coffee and caffeine intake and T2DM incidence.
  
  
  METHODS
  Pertinent studies were identified by a search of PubMed and EMBASE. The fixed- or random-effect pooled measure was selected based on between-study heterogeneity. Dose-response relationship was assessed by restricted cubic spline.
  
  
  RESULTS
  Compared with the lowest level, the pooled relative risk (95 % CI) of T2DM was 0.71 (0.67-0.76) for the highest level of coffee intake (26 articles involving 50,595 T2DM cases and 1,096,647 participants), 0.79 (0.69-0.91) for the highest level of decaffeinated coffee intake (10 articles involving 29,165 T2DM cases and 491,485 participants) and 0.70 (0.65-0.75) for the highest level of caffeine intake (6 articles involving 9,302 T2DM cases and 321,960 participants). The association of coffee, decaffeinated coffee and caffeine intake with T2DM incidence was stronger for women than that for men. A stronger association of coffee intake with T2DM incidence was found for non-smokers and subjects with body mass index <25 kg/m(2). Dose-response analysis suggested that incidence of T2DM decreased by 12 % [0.88 (0.86-0.90)] for every 2 cups/day increment in coffee intake, 11 % [0.89 (0.82-0.98)] for every 2 cups/day increment in decaffeinated coffee intake and 14 % [0.86 (0.82-0.91)] for every 200 mg/day increment in caffeine intake.
  
  
  CONCLUSIONS
  Coffee and caffeine intake might significantly reduce the incidence of T2DM.
authors.affiliation: Department of Epidemiology and Health Statistics, Medical College, Qingdao University, No. 38 Dongzhou Road, Qingdao, 266021, Shandong, People's Republic of China.
authors.forename: Xiubo
authors.initials: X
authors.lastname: Jiang
authors.forename: Dongfeng
authors.initials: D
authors.lastname: Zhang
authors.forename: Wenjie
authors.initials: W
authors.lastname: Jiang
mesh_terms: D015992:Body Mass Index; D002110:Caffeine / Q000008:administration & dosage*; D003069:Coffee / Q000737:chemistry*; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology* / Q000517:prevention & control; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors
chemical_list: D003069:Coffee; D002110:Caffeine