title: Plasma bicarbonate and risk of type 2 diabetes mellitus.
abstract: BACKGROUND
  Several biomarkers of metabolic acidosis, including lower plasma bicarbonate and higher anion gap, have been associated with greater insulin resistance in cross-sectional studies. We sought to examine whether lower plasma bicarbonate is associated with the development of type 2 diabetes mellitus in a prospective study.
  
  
  METHODS
  We conducted a prospective, nested case-control study within the Nurses' Health Study. Plasma bicarbonate was measured in 630 women who did not have type 2 diabetes mellitus at the time of blood draw in 1989-1990 but developed type 2 diabetes mellitus during 10 years of follow-up. Controls were matched according to age, ethnic background, fasting status and date of blood draw. We used logistic regression to calculate odds ratios (ORs) for diabetes by category of baseline plasma bicarbonate.
  
  
  RESULTS
  After adjustment for matching factors, body mass index, plasma creatinine level and history of hypertension, women with plasma bicarbonate above the median level had lower odds of diabetes (OR 0.76, 95% confidence interval [CI] 0.60-0.96) compared with women below the median level. Those in the second (OR 0.92, 95% CI 0.67-1.25), third (OR 0.70, 95% CI 0.51-0.97) and fourth (OR 0.75, 95% CI 0.54-1.05) quartiles of plasma bicarbonate had lower odds of diabetes compared with those in the lowest quartile (p for trend = 0.04). Further adjustment for C-reactive protein did not alter these findings.
  
  
  CONCLUSIONS
  Higher plasma bicarbonate levels were associated with lower odds of incident type 2 diabetes mellitus among women in the Nurses' Health Study. Further studies are needed to confirm this finding in different populations and to elucidate the mechanism for this relation.
authors: Renal Division, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, MA, USA. emandel@partners.org
authors: Ernest I
authors: EI
authors: Mandel
authors: Gary C
authors: GC
authors: Curhan
authors: Frank B
authors: FB
authors: Hu
authors: Eric N
authors: EN
authors: Taylor
mesh_terms: D000328:Adult; D001639:Bicarbonates / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000209:etiology; D005260:Female; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D016017:Odds Ratio; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D001639:Bicarbonates; D015415:Biomarkers