The differential diagnosis for children with diabetes includes a group of monogenic diabetic disorders known as
maturity-onset diabetes of the young (
MODY). So far, six underlying gene defects have been identified. The most common subtypes are caused by mutations in the genes encoding the
transcription factor HNF-1a (
MODY 3) and the glycolytic
enzyme glucokinase (GCK) (
MODY 2).
MODY 2 is the most benign form of diabetes as the threshold for
glucose sensing is elevated resulting in mild, regulated
hyperglycemia.
MODY 2 may usually be treated with diet alone without risk of microvascular complications. Patients with
MODY usually present as children or young adults. Genetic testing for
MODY in diabetic subjects is often not performed because of the costs and its unavailability in Switzerland. We describe the impact of the genetic analysis for
MODY 2 on diabetes management and treatment costs in a five-year-old girl. The patient and her diabetic mother were both found to have a heterozygous missense mutation (V203A) in the
glucokinase gene. The five-year-old girl was started on
insulin therapy for her diabetes but because her HbA1c remained between 5.8-6.4% (reference 4.1-5.7%) and her clinical presentation suggested
MODY insulin was discontinued. She is now well controlled on a
carbohydrate controlled diet regimen only. Omission of
insulin treatment made regular
blood glucose monitoring unnecessary and removed her risk of
hypoglycemia. Costs for the genetic analysis were 500 Euro. At our centre costs for diabetes care of a patient with
type 1 diabetes are approximately 2050 Euro/year compared to 410 Euro/year for the care of a patient with
MODY 2. In addition, a diagnosis of
MODY 2 may reassure patients and their families, as microvascular complications are uncommon. Thus there are both health and financial benefits in diagnosing
MODY 2. We recommend genetic testing for
MODY 2 in clinically selected patients even though this analysis is currently not available in Switzerland and costs are not necessarily covered by the health insurances.