Expert Blog

MODY: An Increasingly Important and Often Overlooked Form of Diabetes

Kevin A. Peterson, MD, MPH
Family Medicine
 Dr. Leahy and Dr. Hirsch provide a great introduction to the very latest info on MODY!  Dr. Leahy’s frank discussion of practical diagnostic considerations in patients with hyperglycemia who do not easily fit into the classification of type 1 or type 2 diabetes provides a refreshing look at how we practice today and a peek at how we may practice in the future. Dr. Hirsch provides a valuable physiologic perspective detailing how and why treatment approaches differ between type 1 or type 2 diabetes and various types of MODY.   Although MODY isn’t common, it is variation of diabetes that is increasingly important for primary care providers to recognize. 
In the past distinguishing MODY from other forms of diabetes hasn’t mattered very much. An individual with MODY was treated like everyone else with Type 1 or Type 2 diabetes, so the diagnosis was only of academic interest. But as we continue to unravel the genetic code, distinguishing individuals with MODY can increasingly influence medication options, change risk assessments, and provide important information for patients and families.    
Everyone in clinical practice encounters individuals with unusual presentations of diabetes.  During the TRANSLATE trial in which over 13,500 patients with diabetes from 24 community primary care practices were reviewed , 2.5% of patients were unable to be distinguished by experts as  having either type 1 or type 2 diabetes.[1] )   These patients and their providers often recognize that their form of hyperglycemia is different, and that some of the typical rules of diabetes care don’t apply.   Unusual presentations of common diseases are an axiom for primary care providers.  But MODY is an unusual form of diabetes, and common presentations of MODY remain widely unrecognized in primary care settings.  
Currently MODY includes only a few monogenic forms of diabetes, but the list is likely to grow. We recognize Type 2 diabetes as a polygenic disease that is further influenced by environmental factors like obesity. However even type 2 diabetes is likely to have common variations in polygenetic patterns that influence treatment or risk. As we better understand those genetic influences, the diagnosis of type 2 diabetes may need to become more refined.  
Two hundred years ago the diagnosis of “dropsy” was a vague aggregation of rapidly fatal conditions that was made obsolete by a better understanding of cardiovascular disease.    In the future, it is possible that a better understanding of the genetics of hyperglycemia will make a diagnosis of type 2 diabetes similarly appear as a vague aggregation of several etiologies.   For now, Dr. Leahy and Dr Hirsch help to underline the idea that primary care providers need to step beyond checking the type 1 or type 2 box when making a diagnosis of diabetes. Recognizing the possibility of MODY provides a new perspective when initiating therapy. A little suspicion may inform our clinical insight and remind us that an unusual presentation might be pointing to an unusual form of a common disease.