title: Variation in TCF7L2 influences therapeutic response to sulfonylureas: a GoDARTs study.
abstract: OBJECTIVE
  There is considerable interindividual variation in sulfonylurea response in type 2 diabetes. Transcription factor 7-like 2 (TCF7L2) variants have been identified to be strongly associated with type 2 diabetes risk, probably due to decreased beta-cell function. We hypothesized that variation in TCF7L2 would influence response to sulfonylureas but not metformin. We studied the effect of TCF7L2 rs12255372 and rs7903146 genotypes on glycemic response.
  
  
  METHODS
  The DARTS/MEMO (Diabetes Audit and Research Tayside/Medicines Monitoring Unit) collaboration database includes prescribing, biochemistry, and clinical phenotype of all patients with diabetes within Tayside, Scotland, from 1992. Of these, the TCF7L2 genotype was determined in 4,469 patients with type 2 diabetes recruited to GoDARTS (Genetics of Diabetes Audit and Research Tayside) between 1997 and July 2006. A total of 901 incident sulfonylurea users and 945 metformin users were identified. A logistic regression was used with treatment failure defined as an A1C >7% within 3-12 months after treatment initiation. Covariates included the TCF7L2 genotype, BMI, sex, age diagnosed, drug adherence, and drug dose. A1C pretreatment was available in a subset of patients (sulfonylurea n = 579; metformin n = 755).
  
  
  RESULTS
  Carriers of the risk allele were less likely to respond to sulfonylureas with an odds ratio (OR) for failure of 1.95 (95% CI 1.23-3.06; P = 0.005), comparing rs12255372 T/T vs. G/G. Including the baseline A1C strengthened this association (OR 2.16 [95% CI 1.21-3.86], P = 0.009). A similar, although slightly weaker, association was seen with rs7903146. No association was seen between metformin response and either single nucleotide polymorphism, after adjustment for baseline A1C.
  
  
  CONCLUSIONS
  TCF7L2 variants influence therapeutic response to sulfonylureas but not metformin. This study establishes that genetic variation can alter response to therapy in type 2 diabetes.
authors.affiliation: Division of Medicine and Therapeutics, University of Dundee, Dundee, UK. e.pearson@chs.dundee.ac.uk
authors.forename: Ewan R
authors.initials: ER
authors.lastname: Pearson
authors.forename: Louise A
authors.initials: LA
authors.lastname: Donnelly
authors.forename: Charlotte
authors.initials: C
authors.lastname: Kimber
authors.forename: Adrian
authors.initials: A
authors.lastname: Whitley
authors.forename: Alex S F
authors.initials: AS
authors.lastname: Doney
authors.forename: Mark I
authors.initials: MI
authors.lastname: McCarthy
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Hattersley
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Morris
authors.forename: Colin N A
authors.initials: CN
authors.lastname: Palmer
mesh_terms: D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology; D005260:Female; D014644:Genetic Variation / Q000235:genetics*; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D013453:Sulfonylurea Compounds / Q000627:therapeutic use*; D051820:TCF Transcription Factors / Q000235:genetics*; D058118:Transcription Factor 7-Like 2 Protein
chemical_list: D013453:Sulfonylurea Compounds; D051820:TCF Transcription Factors; C544894:TCF7L2 protein, human; D058118:Transcription Factor 7-Like 2 Protein