Future of Diabetes Diagnosis, with Help from Pharmacogenetics: Dozens of Type 2 Subtypes

Personalized health care in the context of diabetes, and especially Type 2, someday is likely to involve the diagnosis of patients with one of multiple diabetes subtypes based on an individual’s biological symptoms, physical characteristics and genetic profile, according to Ewan Pearson, a clinical senior lecturer at the University of Dundee in Scotland.

Speaking at a plenary session of the 2012 Global Diabetes Summit hosted by Ohio State’s Diabetes Research Center at Wexner Medical Center, Pearson outlined how stratifying diabetes patients by the origins of their disease and genetic predispositions that influence their response to drugs could dramatically change how patients are treated.

This practice could be a long way off, he said, or, “Who knows? This might not be too far away.”

Pearson, also honorary consultant in diabetes & endocrinology at Ninewells Hospital and Medical School, said the current approach to diabetes diagnosis is oversimplified, with the vast majority of cases defined as Type 2 diabetes. Only a tiny percentage are diagnosed as MODY – maturity onset diabetes of the young.

Detailing a number of case studies that make it abundantly clear how different Type 2 diabetes patients can be in terms of biological symptoms and sensitivity to drugs, Pearson suggested that MODY is not considered frequently enough as an alternative diagnosis to Type 2.

Personalized drug treatment could be much more effective in these stratified patients because their genes would offer clues about which medications, and at which doses, will work best for them. For example, studies have already uncovered gene variants that can affect how statins work at different doses – and roughly 90 percent of diabetes patients take these drugs to control cholesterol.

Similar pharmacogenetic research into genetic variants that influence sensitivity to blood sugar-lowering drugs are in their earliest stages. Pearson and colleagues have identified a likely target gene on chromosome 11 that influences the effects of metformin, an enormously popular drug for lowering blood sugar in Type 2 diabetes, but much more work is required to fully understand that gene’s role. Scientists also have some hints about variants that influence response to another class of glucose-control agents as well.

In cases where variants have been identified that affect patient response to drugs, however, the effects are too limited or affect too few people to justify incorporating genomic analysis into clinical care at this point, he noted.

Pearson asserted that pharmacogenetics will continue to advance discoveries that will have clear implications and lead to “good clinical medicine” that will avoid oversimplification.

“I do think this is the future of diabetes and I’m optimistic that we’ll start identifying some subtypes over the course of the next 5 years,” he said.

-Emily Caldwell


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