Study to Understand the Genetics of the Acute Response to Metformin and Glipizide in Humans

The SUGAR-MGH investigators are studying the influence of inherited gene variants on the response to two commonly prescribed type 2 diabetes medications, metformin and glipizide. They hypothesize that variants in genes that are associated with type 2 diabetes or related traits may impact the effect of anti-diabetic medications. In addition, physiological responses to an insulin secretagogue or an insulin sensitizer may shed light on the mechanism of action of reported genetic associations.

Several common genetic variants have been reliably associated with type 2 diabetes and related glycemic traits. Study investigators hypothesize that variants in genes that are reproducibly associated with type 2 diabetes or related glycemic traits may impact the effect of anti-diabetic medications. In particular, sulfonylureas may have differential effects on individuals depending on the allelic variant they carry at KCNJ11 E23K; conversely, because TCF7L2 is postulated to influence insulin secretion by regulating the action of glucagon-like peptide 1 (GLP-1), and sulfonylureas act at a different step in the insulin secretion pathway, the effect of sulfonylureas on insulin secretion could be independent of genetic variation at TCF7L2. In addition, physiological responses to an insulin secretagogue or an insulin sensitizer may shed light on the mechanism of action of reported genetic associations. Despite the convincing associations of several genetic variants with type 2 diabetes and their involvement in physiological pathways involved in drug response, their impact on pharmacological interventions has not been systematically examined. The completion of the Human Genome Project and the high-density characterization of common human variation in four different ethnic groups highlight the promise of genomic medicine. The elucidation of the genetic architecture of complex phenotypes may help clinicians understand disease heterogeneity, uncover new pathophysiological mechanisms, open the opportunity for novel therapeutic interventions, provide predictive diagnostic and prognostic information, and allow for individually tailored therapy that takes into account both the probability of response and the incidence of drug-induced complications.