MODY typically presents in the second to fourth decade of life, and does not fit the clinical picture of either types 1 or 2 diabetes. Presentation is often subacute or incidental. Many cases are misdiagnosed as types 1 or 2 diabetes.2,3
MODY is the only type of diabetes caused by a single gene mutation. Mutations in 13 genes are known to cause MODY. The most prevalent mutations are in the HNF1A, GCK and HNF4A genes. GCK-MODY constitutes 10–60% of all MODY cases.2
Testing for MODY should be considered in individuals with early onset diabetes with atypical features (ie not clearly type 1 or type 2):1
- atypical type 1 diabetes
- no history of diabetic ketoacidosis
- prandial plasma C-peptide >200 pmol/L and >5 years post-diagnosis of type 1 diabetes
- atypical type 2 diabetes
- <35 years of age
- absence of features of insulin resistance
- no obesity
- no dyslipidaemia
- no hypertension
- no polycystic ovary syndrome
- strong family history of diabetes.
If MODY is suspected, assess risk using the calculator available.