Understanding Diabetes 

What is MODY Diabetes – A Simple Explanation

What is Mody Diabetes – Maturity onset diabetes of the young

MODY is a monogenic form of diabetes that is often confused with type 1 or type 2 diabetes. MODY decreases the amount of insulin a person’s body makes, which in turn limits the body’s ability to control the amount of sugar (glucose) in the blood.

MODY is a rare form of diabetes which is different from both Type 1 and Type 2 diabetes, which are caused by changes in many genes and/or other factors such as being overweight or having high blood pressure. Mody runs strongly in families and is caused by a mutation (or change) in a single gene. If a parent has this gene mutation, any child they have, has a 50 per cent chance of inheriting it from them.

If a child does inherit the mutation they will generally go on to develop MODY before they’re 25, whatever their weight, lifestyle, ethnic group etc.

Only 1–2 per cent of people with diabetes (20-40,000 people) in the UK have it. But because MODY is so rare, doctors may not be aware of it, so it’s estimated that about 90 per cent of people with it are mistakenly diagnosed with Type 1 or Type 2 diabetes at first.

MODY usually develops during childhood or early adulthood but sometimes remains undiagnosed until later in life. Because MODY is inherited, people with MODY may have other family members with symptoms of diabetes. Over half a million people in the United States have MODY. That makes it about as common as type 1 diabetes.

Signs And Symptoms of MODY

Signs and symptoms of Maturity Onset Diabetes of the Young (MODY) tend to develop gradually. This is similar to the clinical course of type 2 diabetes, which develops slowly over a period of several months or years unlike type 1 diabetes in which symptoms develop rather quickly i.e. over a few weeks.

Many people with MODY may have elevated blood sugar (hyperglycemia) for many years before they develop any symptoms. The high blood sugar may be diagnosed accidentally such as during a routine health check-up. In early stages, the person may have no symptoms, but without treatment, blood sugar will continue to rise thereby causing the following symptoms:

  • Increased thirst: rise in blood sugar levels causes the fluids to move out of the cells in the body. The loss of fluid from the cells makes one feel thirsty and therefore, a person with such a diabetic condition drinks more water.
  • Frequent urination: rise in blood sugar causes fluids to move out of the cells and you to drink more fluid. When you drink more fluid, you are likely to urinate more frequently. The increased frequency of urination is present both during the day and at night.
  • Increased hunger: in diabetes, there is plenty of sugar in the blood, but the cells of the body fail to use it due to a lack of insulin; this gets the cells deprived of an energy source and therefore, the patient feels hungry more frequently.
  • Weight loss: as glucose (blood sugar) is not used efficiently and spills into urine from the blood, it causes loss of nutrient from body and weight loss (though appetite often increases).
  • Blurred vision: Elevated glucose levels in the blood leads to loss of fluid from the lenses of the eyes thereby, affecting your ability to focus and see clearly.

In contrast, many people with MODY have no signs or symptoms and are diagnosed either by accident, when a high glucose is discovered during testing for other reasons, or screening of relatives of a person discovered to have diabetes. Discovery of mild hyperglycemia during a routine glucose tolerance test for pregnancy is particularly characteristic.

A person may have MODY if these things are true:

  • Has high blood sugar that was discovered before age 30 (though anyone underage 50 may have MODY)
  • Has a close family member with diabetes, such as a parent or sibling
  • Does not need much insulin to regulate blood sugar
  • Is not overweight, although overweight or obese people may also have MODY
  • Does not have high blood pressure or high cholesterol
  • Is not resistant to insulin
  • Was diagnosed with type 1 diabetes before 6 months of age

The good news is that there is a genetic test for MODY. This test can help diagnose most people who have MODY. If you or your child has symptoms that could be caused by MODY, talk with a doctor about whether genetic testing might be the right choice for you or your family.

Treatment For MODY

Treatment is tailored to the type of MODY you have. In general, MODY patients are treated with some or all of the following:

  • Meal planning
  • Oral diabetes medications
  • Low doses of insulin

You and your doctor will discuss whether oral medication will help control your blood sugar. MODY 1, MODY 3 and MODY 4 usually respond well to one particular type of medication, called sulfonylureas, it causes your pancreas to produce more insulin.

MODY 5 and MODY 6 patients use insulin for treatment, as do some MODY 1, MODY 3 and MODY 4 patients.

MODY 2 patients typically respond well to diet and exercise.

KLF11 has been associated with a form of diabetes that has been characterized as “MODY7” by OMIM.

Sub-types of Mody and the genes affected

Due to any of several mutations in the GCK gene. 30%–70% cases. Mild fasting hyperglycemia throughout life. Small rise on glucose loading. Patients do not tend to get diabetes complications and do not require treatment.

Type OMIM Gene/protein Description
MODY 1 125850 hepatocyte nuclear factor 4α Due to a loss-of-function mutation in the HNF4α gene. 5%–10% cases.
MODY 2 125851 glucokinase
MODY 3 600496 hepatocyte nuclear factor 1α Mutations of the HNF1α gene (a homeobox gene). 30%–70% cases. Tend to be responsive to sulfonylureas. Low renal threshold for glucose.
MODY 4 606392 insulin promoter factor-1 Mutations of the IPF1 homeobox (Pdx1) gene. < 1% cases. Associated with pancreatic agensis in homozygotes and occasionally in heterozygotes.
MODY 5 137920 hepatocyte nuclear factor 1β One of the less common forms of MODY, with some distinctive clinical features, including atrophy of the pancreas and several forms of renal disease. Defect in HNF-1 beta gene. 5%–10% cases.
MODY 6 606394 neurogenic differentiation 1 Mutations of the gene for the transcription factor referred to as neurogenic differentiation 1. Very rare: 5 families reported to date.
MODY 7 610508 Kruppel-like factor 11
MODY 8 609812 Bile salt dependent lipase CEL has been associated with a form of diabetes[that has been characterized as “MODY8” by OMIM. It is very rare with five families reported to date. It is associated with exocrine pancreatic dysfunction.
MODY 9 612225 PAX4 Pax4 is a transcription factor. MODY 9 is a very rare medical condition.
MODY 10 613370 INS Mutations in the insulin gene. Usually associated with neonatal diabetes. Rare < 1% cases.
MODY 11 613375 BLK Mutated B-lymphocyte tyrosin kinase, which is also present in pancreatic islet cells. Very rare.
Permanent neonatal diabetes mellitus 606176 KCNJ11 and ABCC8 A newly identified and potentially treatable form of monogenic diabetes is the neonatal diabetes caused by activating mutations of the ABCC8 or KCNJ11 genes which encode sub units of the KATP channel. < 1% cases. Tend to respond to sulfonylureas.
Transient neonatal diabetes mellitus 601410
610374
610582
ABCC8 Some forms of neonatal-onset diabetes are not permanent. < 1% cases. Tend to respond to sulfonylureas.

Conclusion

It is important to consider monogenic diabetes in young patients with non-acute presentation of diabetes, absence of beta-cell autoimmunity, and no signs of insulin resistance. Careful monitoring and rapid referral for genetic testing can establish optimal treatment and avoid insulin use. Identifying Mody remains a challenge for doctors to identify and the condition is largely under diagnosed.

Thanks for reading this article, if you have any questions feel free to leave them below and I will be more than happy to help you out.

Regards

Garry (Type 1)

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