title: Relationship between HbA1c and risk of all-cause hospital admissions among people with Type 2 diabetes.
abstract: OBJECTIVE
  To investigate the relationship between HbA(1c) and the 2-year risk of hospitalization among people with Type 2 diabetes.
  
  
  METHODS
  In total, 4704 patients from 18 general practices in Cambridgeshire were included. Glycaemic exposure was assessed in 2008-2009. The primary outcome was all-cause hospital admissions in 2010-2011. Adjusted relative risks for each HbA(1c) quintile were estimated using Cox models. Further relationships between HbA(1c) and risks were explored using spline models.
  
  
  RESULTS
  There was a non-linear relationship between HbA(1c) and the risk of all-cause, diabetes and vascular admissions (all P < 0.001 for linearity test) with an HbA(1c) threshold of 61 (95% CI 55-66) mmol/mol [7.7 (95% CI 7.2-8.2)%]. For every 11 mmol/mol (1%) HbA(1c) above the threshold, the risks increased by 6.3% for all-cause admission, 6.4% for a diabetes admission and 15.9% for a cardiovascular admission (all P < 0.001). The overall hospitalization risks of having an HbA(1c) above, rather than at, the threshold, were 19.1 16.3 and 54.3% greater, respectively. There were non-significantly greater risks of hospital admission below the threshold.
  
  
  CONCLUSIONS
  In people with Type 2 diabetes, a non-linear relationship exists between HbA(1c) and the risk of hospitalization. A threshold of 61 mmol/mol (7.7%) was associated with the lowest rate of all-cause hospital admissions. Further research should investigate the causes of admissions below and above this threshold, with a view to developing strategies to reduce the excess hospitalization among patients with diabetes.
authors.affiliation: Institute of Metabolic Science, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
authors.forename: D
authors.initials: D
authors.lastname: Yu
authors.forename: D
authors.initials: D
authors.lastname: Simmons
mesh_terms: D000368:Aged; D000959:Antihypertensive Agents / Q000627:therapeutic use; D001786:Blood Glucose / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000150:complications / Q000401:mortality; D003925:Diabetic Angiopathies / Q000097:blood* / Q000209:etiology / Q000401:mortality; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D006943:Hyperglycemia / Q000097:blood* / Q000401:mortality; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D008297:Male; D010343:Patient Admission / Q000706:statistics & numerical data; D016016:Proportional Hazards Models; D012307:Risk Factors; D006113:United Kingdom / Q000453:epidemiology
chemical_list: D000959:Antihypertensive Agents; D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007004:Hypoglycemic Agents; C517652:hemoglobin A1c protein, human