Differentials
Monogenic diabetes: maturity onset diabetes of the young
SIGNS / SYMPTOMS
Maturity-onset diabetes of the young (MODY) is the most common form of monogenic diabetes and affects 1% to 2% of people with diabetes.[43]
MODY is caused by mutation of a single gene (i.e., monogenic). It has autosomal dominant inheritance and should be suspected in cases of diabetes in non-obese, young patients (adolescence or young adult) with family history of diabetes in two or more successive generations.[44]
Presents with non-ketotic, non-insulin-dependent diabetes that responds to oral glucose lowering drugs.[45]
INVESTIGATIONS
C-peptide present.
Autoantibodies absent.
Genetic testing in patients with high index of suspicion identifies mutations most commonly in genes encoding glucokinase and transcription factors.[45]
Neonatal diabetes
SIGNS / SYMPTOMS
Diabetes diagnosed under 6 months of age.[46]
Usually isolated diabetes in an autosomal dominant pattern of inheritance.
Some monogenic causes are characterised by a variety of syndromic features.[47]
INVESTIGATIONS
Genetic testing with majority of mutations in the genes encoding the adenosine triphosphate-sensitive potassium channel and the insulin gene.[47]
Latent autoimmune diabetes in adults (LADA)
SIGNS / SYMPTOMS
Typical age of onset of diabetes is over 30 years old. Patients are usually non-obese and respond initially to lifestyle modifications and oral agents. Production of insulin gradually decreases (between 6 months and 5 years), such that treatment with insulin is required.[2]
LADA is considered a subset of type 1 diabetes; however, patients with LADA are frequently misclassified as having type 2 diabetes.
INVESTIGATIONS
Low to normal initial C-peptide level.
Can be positive for at least 1 of the 4 antibodies commonly found in type 1 diabetic patients.[2]
Type 2 diabetes
SIGNS / SYMPTOMS
Typically, signs of insulin resistance (such as acanthosis nigricans) should be sought and in their absence clinical suspicion of type 1 diabetes is greater.
Signs of more marked insulin deficiency (for example, glycaemic lability as well as susceptibility to ketosis) raise suspicion of type 1 diabetes.
Older age and slow onset, obesity, a strong family history, absence of ketoacidosis, and initial response to oral anti-hyperglycaemic drugs are typical of type 2 diabetes.
INVESTIGATIONS
C-peptide present.
Autoantibodies absent.
Testing for C-peptide and autoantibodies usually not required.
Use of this content is subject to our disclaimer