Pharmacogenetics

The study of genetic variations that can affect how an individual responds to specific drugs, in terms of both effectiveness and adverse events. The study of pharmacogenetics can help doctors improve the effectiveness and lower the risks associated with various drugs. Pharmacogenetics may someday play an important role in the treatment of an assortment of medical conditions.

There are now more than 10 classes of drugs for treating diabetes, each of which works through a different biochemical pathway in the body. People can respond very differently to the same class of drugs — in other words, each drug effectively lowers blood glucose levels in some people but not in others, and it is difficult to predict who will respond well to which drugs. Individual genetic differences may help account for these variations in effectiveness.

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Already, pharmacogenetics has influenced the treatment of two rare forms of diabetes that arise from single genetic mutations. One of these forms is maturity-onset diabetes of the young (MODY), which is characterized by onset at a young age and a pattern that fits more with Type 2 diabetes than Type 1. People with MODY have a genetic mutation that affects the development of pancreatic beta cells and insulin production. They respond better to the sulfonylurea class of drugs, which stimulate insulin secretion, than to metformin, which improves insulin sensitivity. Neonatal diabetes, which is diagnosed on the basis of hyperglycemia (high blood glucose) within the first six months of life, is sometimes mistakenly diagnosed as Type 1 diabetes and treated with insulin. Once the correct genetic diagnosis is made, these babies can be switched from insulin to high doses of a sulfonylurea.

The potential role of pharmacogenetics in Type 2 diabetes, the most common form of diabetes, remains to be seen. Over 40 genetic variants are seen more commonly in people with Type 2 diabetes, but which specific genes actually play a role in causing Type 2 diabetes is not yet fully understood. Likewise, the biological mechanisms by which certain diabetes drugs work is not fully understood. Still, researchers have found certain genetic variations that may influence the effectiveness of sulfonylureas and metformin. Research on the pharmacogenetics of Type 2 diabetes is still in its infancy.

Want to learn more about the role of medicines in treating diabetes? Read diabetes educator Amy Campbell’s eight-part series on diabetes drugs, covering metformin, sulfonylureas, meglitinides, thiazolidinediones, DPP-4 inhibitors, SGLT2 inhibitors, alpha-glucosidase inhibitors, bile acid sequestrants and dopamine receptor agonists, non-insulin injectable diabetes medications, and insulin.