Monogenic Diabetes

The most common types of diabetes are type 1 and type 2 diabetes. Along with gestational and LADA, these forms of diabetes are polygenic diseases that require the involvement of many genes and a wide variety of environmental factors to cause each disease. There are some rare forms of diabetes, Maturity Onset Diabetes of the Young (MODY) and Neonatal Diabetes Mellitus (NDM) that are monogenic where only one gene is responsible for the disease. Of the 30,000 genes in the human body, about 20 genes have been linked to monogenic diabetes so far.

Maturity Onset Diabetes of the Young (MODY)

MODY is a monogenic form of diabetes that decreases the body’s ability to control the amount of glucose in the blood. Because of this, it is often confused with type 1 or type 2 diabetes. It is believed up to 2 percent of diabetes cases are due to MODY. MODY usually presents itself in childhood or adolescence but its symptoms can be so mild they are overlooked until a person is older. People with MODY are usually of normal weight and don’t have high blood pressure or high cholesterol like those with type 2.

You should be tested for MODY if you are a:

  • part of a family with 3 consecutive generations of diabetes (about a 50% chance of passing MODY to children, increased chance if more families members have MODY)
  • diabetes patient with stable, mildly elevated blood sugars, often found incidentally during a routine check-up
  • type 1 diabetes patients whose blood tests for autoantibodies are negative. Tests are typically done at the time of diabetes diagnosis (antibodies typically tested include one or more of the following: GAD65, islet cell or ICA, IA-2, insulin, ZnT8)
  • type 1 diabetes patient who generates a significant amount of insulin years beyond diagnosis (detectable blood levels of c-peptide, proinsulin, and/ or insulin)
  • type 2 diabetes patient who is normal weight or not significantly overweight and shows no signs of insulin resistance
  • a person with diabetes paired with pancreatic insufficiency (the digestive role of the pancreas is impaired with symptoms such as diarrhea and gas)
  • Individual or family history of diabetes paired with developmental kidney disease or abnormalities of the kidney (especially cysts). The urinary system and reproductive organs may also be abnormally formed.

Neonatal Diabetes Mellitus (NDM)

NDM can occur from birth to 6 months. Anyone diagnosed with diabetes at or before 12 months should be tested for neonatal diabetes. It can be permanent, called permanent neonatal diabetes mellitus, and require treatment for your entire life or transient, called transient neonatal diabetes mellitus, that can go away and not require treatment. It very likely that diabetes will return later in life so ongoing testing for reoccurrence is suggested.
It can be hard to tell type 1 and neonatal diabetes apart because of shared symptoms. In both types, you can see elevated levels of glucose in the blood,  frequent urination, severe thirst, and dehydration. In extreme cases, the baby may experience ketoacidosis, a condition in which acid levels in the body rise to very dangerous or even life-threatening levels. The only definitive way to diagnose monogenic neonatal diabetes is with genetic testing.

You should be tested for neonatal diabetes if:

  • you were diagnosed with diabetes before 6 months of age

Other forms of monogenic diabetes have more serious effects on blood sugar levels and will cause long-term complications without treatment. Patients might need frequent insulin injections and other medical interventions. Treatment of MODY is dependent on the gene that has the mutation.

Other Monogenic Diabetes Links:

Diabetes International Foundation