Cytochrome P450 2C9 *2 and *3 polymorphisms and the dose and effect of sulfonylurea in type II diabetes mellitus

Clin Pharmacol Ther. 2008 Feb;83(2):288-92. doi: 10.1038/sj.clpt.6100273. Epub 2007 Jun 27.


Sulfonylurea hypoglycemics are mainly metabolized by the cytochrome P450 2C9 (CYP2C9) enzyme. The CYP2C9*2 and *3 polymorphisms encode proteins with less enzymatic activity and are correlated with elevated serum levels of sulfonylurea, as demonstrated in healthy volunteers. In this study, the effect of these variants is described for patients with diabetes mellitus treated with sulfonylurea. Associations between CYP2C9 polymorphisms, prescribed doses of sulfonylurea, and change in glucose levels after the start of sulfonylurea therapy were assessed in all patients with incident diabetes mellitus starting on sulfonylurea therapy in the Rotterdam Study, a population-based cohort study of 7,983 elderly people. In CYP2C9*3 allele carriers using tolbutamide, the prescribed dose was lower compared to patients with the wild-type CYP2C9 genotype. No differences in the prescribed dose were found in tolbutamide users with the CYP2C9*1/*2 or CYP2C9*2/*2 genotype compared to wild-type patients or in patients using other sulfonylurea. In CYP2C9*3 allele carriers, the mean decrease in fasting serum glucose levels after the start of tolbutamide therapy was larger than in patients with the wild-type genotype, although not statistically significant. Patients with diabetes mellitus who are carriers of a CYP2C9*3 allele require lower doses of tolbutamide to regulate their serum glucose levels compared to patients with the wild-type genotype.

MeSH terms

  • Aged
  • Aryl Hydrocarbon Hydroxylases / genetics*
  • Aryl Hydrocarbon Hydroxylases / metabolism
  • Blood Glucose / drug effects*
  • Cytochrome P-450 CYP2C9
  • Diabetes Mellitus, Type 2 / drug therapy*
  • Diabetes Mellitus, Type 2 / enzymology
  • Diabetes Mellitus, Type 2 / genetics
  • Dose-Response Relationship, Drug
  • Drug Prescriptions
  • Female
  • Follow-Up Studies
  • Gene Frequency
  • Genotype
  • Humans
  • Hypoglycemic Agents / administration & dosage
  • Hypoglycemic Agents / pharmacokinetics*
  • Male
  • Middle Aged
  • Phenotype
  • Polymorphism, Genetic*
  • Population Surveillance
  • Prospective Studies
  • Sulfonylurea Compounds / administration & dosage
  • Sulfonylurea Compounds / pharmacokinetics*
  • Time Factors
  • Tolbutamide / pharmacokinetics
  • Treatment Outcome


  • Blood Glucose
  • Hypoglycemic Agents
  • Sulfonylurea Compounds
  • Tolbutamide
  • CYP2C9 protein, human
  • Cytochrome P-450 CYP2C9
  • Aryl Hydrocarbon Hydroxylases