Differentials

SIGNS / SYMPTOMS
INVESTIGATIONS
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.[37]

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.[38]

Presents with non-ketotic, non-insulin-dependent diabetes that responds to oral glucose lowering drugs.[39]

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.[39]

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Diabetes diagnosed under 6 months of age.[1]

Usually isolated diabetes in an autosomal dominant pattern of inheritance.

Some monogenic causes are characterised by a variety of syndromic features.[40]

INVESTIGATIONS

Genetic testing with majority of mutations in the genes encoding the adenosine triphosphate-sensitive potassium channel and the insulin gene.[40]

SIGNS / SYMPTOMS
INVESTIGATIONS
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.[41]

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.[41]

SIGNS / SYMPTOMS
INVESTIGATIONS
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.

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