Understanding Genetic Forms of Diabetes

While type 1, type 2, and gestational diabetes are the most well-known types, there are also rare genetic forms of diabetes that can be inherited. These conditions are distinct from other types of diabetes and require specific diagnostic tests and treatments. Two key genetic forms of diabetes include Maturity-Onset Diabetes of the Young (MODY) and Mitochondrial Diabetes.

Maturity-Onset Diabetes of the Young (MODY)

MODY is a rare form of diabetes caused by a change (mutation) in a single gene. Unlike type 1 or type 2 diabetes, MODY typically develops before the age of 25, often runs in families, and is not linked to lifestyle factors or obesity.

Causes of MODY

MODY is caused by mutations in specific genes that affect insulin production. Some of the most common genes involved include:

  • HNF1A MODY: Leads to a progressive decrease in insulin production and is often mistaken for type 1 or type 2 diabetes.
  • HNF4A MODY: Can be associated with high birth weight and low blood sugar (hypoglycaemia) in newborns.
  • HNF1B MODY: Often linked to kidney abnormalities in addition to diabetes.
  • GCK MODY: Causes slightly elevated blood sugar levels from birth but usually does not require treatment.

Symptoms of MODY

The symptoms of MODY vary depending on the gene affected but may include:

  • Mild to moderate high blood sugar levels
  • Family history of diabetes in multiple generations
  • Diabetes diagnosed at a young age (usually under 25)
  • Lack of autoantibodies typical of type 1 diabetes
  • No association with obesity or insulin resistance

Diagnosing MODY

MODY is often misdiagnosed as type 1 or type 2 diabetes. A genetic test is required to confirm the diagnosis. If you have a strong family history of diabetes diagnosed at a young age, genetic testing may be recommended.

Managing MODY

The treatment for MODY depends on the gene mutation involved. Some forms of MODY can be managed with oral medications instead of insulin, while others may not require treatment at all. It is important to have regular check-ups with a specialist to determine the best treatment plan.

Mitochondrial Diabetes

Mitochondrial diabetes is another rare genetic form of diabetes caused by mutations in mitochondrial DNA, which is inherited from the mother. It can be associated with other health conditions, such as hearing loss.

Causes of Mitochondrial Diabetes

Mitochondrial diabetes is caused by defects in the mitochondria, the part of the cell responsible for energy production. This can lead to problems with insulin secretion and energy metabolism.

Symptoms of Mitochondrial Diabetes

Symptoms may include:

  • High blood sugar levels
  • Hearing loss, particularly before the onset of diabetes
  • Muscle weakness or neurological symptoms
  • Family history of diabetes inherited from the mother

Diagnosing Mitochondrial Diabetes

A genetic test is needed to confirm mitochondrial diabetes. If you have a family history of diabetes and hearing loss, genetic screening may be recommended.

Managing Mitochondrial Diabetes

  • Many people with mitochondrial diabetes require insulin therapy.
  • Some may respond to oral diabetes medications, but treatment plans vary depending on individual needs.
  • Management may also involve treating associated conditions, such as hearing loss or neurological symptoms.

Getting support

Genetic forms of diabetes can be challenging to diagnose and manage. If you suspect you have a genetic form of diabetes, speak to your healthcare provider about genetic testing. Specialist diabetes clinics and genetic counselling services can provide further support and guidance.