Genetic testing clarifies diagnosis and treatment in a family with both HNF1A and type 1 diabetes

Confirming a diagnosis of diabetes may often be straightforward but identifying the actual type of diabetes may not always be obvious, particularly in those with a family history of diabetes. Use of non‐genetic tests, such as pancreatic antibodies, may assist in the classification of diabetes but is not routine practice. The introduction of molecular genetic testing may confirm a diagnosis of monogenic diabetes but may be considered by some health care professionals to be expensive and unnecessary, particularly if treatment change is unlikely. However, a positive genetic result may lead to successful transfer from insulin to sulphonylurea treatment in many cases with improvements in glycaemic control and quality of life.

This paper describes a family with diabetes diagnosed below the age of 22 years in three individuals, and the confirmation of both HNF1A and type 1 diabetes within the family. This case highlights the importance of both genetic and non‐genetic tests in confirming a diagnosis. Copyright © 2009 John Wiley & Sons, Ltd.